US20110162884A1

US20110162884A1 - Method and apparatus for control of a network in hvac and other applications

Info

Publication number: US20110162884A1
Application number: US11/719,351
Authority: US
Inventors: Jan Olof Andersson; Logan Brent Grauer; Robert Christopher Kwong; Glenn William Nichols; Jason John Lemon; Kenneth John Lockhart; Trevor Lewis Rossner; Jeffrey Paul Wiedemann; Chris Edwin Kasian; William Andrew Perrin
Original assignee: Uponor Innovation AB
Priority date: 2004-11-19
Filing date: 2004-11-19
Publication date: 2011-07-07
Also published as: WO2006055013A1; CA2587004C; CA2587004A1; DK1813002T3; EP1813002A1; DE602004031785D1; US20100061396A1; CA2586600A1; NO20072621L; EP1820243A1; EA200700880A1; CA2587005A1; CA2587005C; WO2006055001A1; EA200700882A1; US7936748B2; PT1813002E; SI1813002T1; ES2362663T3; EP1813002B1

Abstract

A system and method for connecting a number of network devices together in a daisy chain configuration is disclosed. A connector device comprising a number of cable interfaces for a cable is used to allow a number of network devices connected to a network to be connected in a free-form manner, yet still maintain a daisy chain configuration. A cable comprising at least two conductors, wherein the conductors are preferably a twisted pair of copper wire, is used to connect the network devices, so that each network device only has a single cable connected to it. Additional network devices can be added to the network by simply connecting the additional network device into the existing network with the use of an additional cable and an additional connector device. Wherever the additional network device is added to the existing network, the network will be maintained in a daisy chain configuration.

Description

This invention is in the field of network connector devices and more specifically systems for connecting networks in a daisy chain configuration.

BACKGROUND

Daisy chaining is the simplest way to connect a network. Devices connected by a daisy chain are connected to one to another in series and a message that is sent on the network has to travel down the chain from one device to another. Compared to other network topologies, daisy chaining is relatively slow, however in applications that do not require large amounts of data transfer and fast transfer rates, daisy chaining is still a common practice and daisy chain networks are still very common in industrial control networks.
One common standard that uses a daisy chain configuration for networking devices is the RS-485 standard. While RS-485 devices may be quite common, there are other protocols that specify or can use a daisy chain network configuration such as Apple's LocalTalk™ and many types of industrial applications.
While networked devices using the RS-485 protocol have always been common in industrial systems, such as larger scale heat and ventilation systems, with the decrease in price of control systems, smaller scale control systems are becoming more common. One area using networked devices that can use a daisy chain topology is home automation and especially home HVAC systems.
In order to setup devices in a daisy chain network, a cable has to be strung to each of the devices in the network. With the exception in some cases of the first and last devices in a daisy chain network, each device in the network requires a cable running to it from a previous device and another cable running from it to the next device. Daisy chaining connections utilizes termination resistors on each end of the network to ensure that every transceiver is directly connected to the main current path. Transceivers placed outside the termination resistors daisy chain may not be able to correctly sense the voltage drop and “hear” the transmission. In this way “star” wiring configurations are not allowed for daisy chained networks such as RS-485.
The disadvantage of wiring the network is this fashion is that there must be some overall plan to the creation of the network. The devices must be planned to some degree because a cable running from the previous device must be connected to the device and a different cable must be run to the next device. This requires the person setting up the network to know where the previous device is as well as the location of the next device. Knowing the placements of the devices may not be overly complicated when the network is small and centralized in one area, but often these daisy chain networks have long distances between devices and these devices might be in different locations that are not in sight of each other. For example, in a HVAC system for a house, the devices connected to the chain network will typically be a controller near the furnace and a number of thermostats connected to the daisy chain network and spread throughout the house. Each thermostat device connected to the network will likely be situated in a different room or location of the house from other devices and it will not always be easy to determine in which direction to run the cable to and from each device.
Additionally, some of the protocols such as RS-485 networks require a termination resistor at the end of the network. This requires one of the devices to serve as the last device and the network must be planned to end at the device that has the termination resistor in it.
Not only must the daisy chain network be planned to some degree, but it can also be complicated to add new devices to the network. To add a new device, the network must be disconnected from one of the device and the new device incorporated into the chain. Again, the location of the previous device and next device must be known, which might not be that easy to determine if the network is spread throughout a large building and numerous rooms.
The different standards for daisy chain networks also specify the type of cable that is required in order to connect the devices. RS-485, for example, specifies certain minimum standards for cable and requires the cable to be a twisted pair in order to use balanced differential signals to reduce or eliminate the effect of interference in the cables.
There are many cables available that meet the recommendations for the different daisy chain network protocols and there are cables that are specially designed for use with these applications. These cables are quite specialized and although daisy chain networks are common, they are not as common as other more standard types of networks. This often makes the special cabling more costly and harder to find because of its lower production. Also, electricians are often not familiar with these types of specialty cables.
In more recent years a number of more standard cable specifications have arisen that are not specifically made for daisy chain networks. One very common type of standard cable is referred to as Category 5 cabling. These standardized cables often include a number of conductors or wire strands and standardized connections to increase the ability of these standard cables to be used in a number of different applications i.e. category 5 consists of four twisted pairs of copper wire terminated by RJ45 connectors.
Because these standard cables can be used in so many applications and circumstances and some, like Category 5 wire, are in common use, they are manufactured in very large quantities which often makes them cheaper then other specialty cables, easier to find and electricians and other installers are more often more familiar with their use.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a system and apparatus that overcomes problems in the prior art.
The present invention provides, in a first embodiment, a Y-connector device for connecting a plurality of network devices in a daisy chain network with cables, wherein each cable comprises two conductors. The apparatus comprises: a first cable interface comprising a pair of conductor connectors, each conductor connector operative to connect one conductor of a connected cable to a connecting circuit; a second cable interface comprising a pair of conductor connectors, each conductor connector operative to connect one conductor of a connected cable to the connecting circuit; a third cable interface comprising a pair of conductor connectors, each conductor connector operative to connect one conductor of a connected cable to the connecting circuit; wherein the connecting circuit is configured such that: one of the conductor connectors of the first cable interface is connected to one of the conductor connectors of the second cable interface; the other of the conductor connectors of the second cable interface is connected to one of the conductor connectors of the third cable interface; and the other of the conductor connectors of the third cable interface is connected to the other of the conductor connectors of the first cable interface.
The present invention provides, in a second embodiment, a system to create a daisy chain network comprising: a plurality of cables, each cable having a first end and a second end and comprising at least two conductors; at least one connector device comprising: a first cable interface operatively and connected to a first cable; a second cable interface operatively connected to a second cable; and a third cable interface operatively connected to a third cable; wherein the connector device will maintain devices connected to it in a daisy chain configuration; at least three network devices each network device operative to communicate as a node in a daisy chain network and each of the network devices operatively connected by a cable to a cable interface of a connector device; wherein each cable interface of each connector device is connected by a cable to one of a network device and another connector device.
The present invention provides, in a third embodiment, a system to create a daisy chain network comprising: a plurality of cables, each cable having a first end and a second end and comprising at least two conductors; at least one connector device comprising: a first cable interface operatively and connected to a first cable; a second cable interface operatively connected to a second cable; and a third cable interface operatively connected to a third cable; wherein the connector device will maintain devices connected to it in a daisy chain configuration; at least three network devices each network device operative to communicate as a node in a daisy chain network and each of the network devices operatively connected by a cable to a cable interface of a connector device; wherein each cable interface of each connector device is connected by a cable to one of a network device and another connector device and wherein the at least one connector device comprises a connecting circuit operatively connected to the cable interfaces wherein the connecting circuit connects: one of the conductors of the first cable to one of the conductors of the second cable; the other conductor of the first cable to one of the conductors of the third cable; and the other conductor of the second cable to the other conductor of the third cable.
In one embodiment of the invention, a wiring scheme is used to connect a number of network devices together in a free form physical architecture while maintaining an electrical daisy chain configuration. A cable comprising at least two conductors is connected to each network device, rather than two cables, with each cable having one conductor, being connected to the network device. Typically, each conductor would be a twisted pair of copper wires. The first conductor typically carries the data from the wiring hub, where the termination resides, while the second conductor is connected to the next network device, to finally end where the other termination resides. This one cable is then connected to a connector device that maintains the network devices connected to it in a daisy chain configuration. Thus this configuration satisfies the electrical “daisy chain” requirement while allowing other cable structures. As longs as each network device is connected to a connector device and all of the connector devices are connected to each other, the network will be in a daisy chain configuration. The present invention does not require a person connecting a network device into the network to know where the previous network device and next network device is, rather all that is necessary is to run a single cable from a connector device to the network device.

DESCRIPTION OF THE DRAWINGS

While the invention is claimed in the concluding portions hereof, preferred embodiments are provided in the accompanying detailed description which may be best understood in conjunction with the accompanying diagrams where like parts in each of the several diagrams are labeled with like numbers, and where:

FIG. 1 is a schematic diagram of a network in a daisy chain configuration in accordance with the prior art;

FIG. 2 is a schematic diagram of one embodiment of a connector device in accordance with the present invention;

FIG. 3 a-3 g are schematic diagrams of further embodiments of connector devices comprising alternate connecting circuits in accordance with the present invention;

FIG. 4 is a schematic diagram of another embodiment of a connector device having four cable interfaces in accordance with the present invention;

FIG. 5 is a schematic diagram of a network connected in a daisy chain configuration in accordance with the present invention;

FIG. 6 a is a schematic diagram of a network in accordance with the present invention;

FIG. 6 b is a schematic diagram of the network of FIG. 6 a with an additional network device added using an additional connector device in accordance with the present invention;

FIG. 6 c is a schematic diagram of the network of FIG. 6 a with the additional network device added in a different manner than in FIG. 6 b; and

FIG. 7 illustrates a network comprising a connector device with a shorting plug.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

FIG. 1 is a schematic illustration of a network 1 in a daisy chain configuration as known in the prior art. In network 1 a number of network devices 120 are connected by a plurality of network cables 5 that connect the network devices in series. Network devices 120 can be any devices that can operate on a daisy chain configuration such as devices that use the RS485 standard. The network cable 5 has a single conductor and in the case of a daisy chain network operating using the RS485 standard, the single conductor would be a twisted pair of copper wires.
In FIG. 1 each network device 120 is connected to two network cables 5. The network is a chain where each network device 120 is connected to two network cables 5, one network cable 5 connecting the network device 120 to the previous network device 120 and another network cable 5 connecting the network device 120 to the next network device 120.
The present invention uses network cable with at least two conductors and a number of connector devices to form a network that allows each network device to be connected to the network by a single cable yet maintain the configuration of a daisy chain network.
FIG. 2 is a schematic illustration of one embodiment of a connector device of the present invention. The connector device 10 illustrated allows network devices (not shown) to be connected by cables (not shown) to the connector device 10 in any fashion and the connector device 10 will ensure that the network devices 120 connected to the connector device 10 by cables will be in a daisy chain configuration. The connector device 10 comprises a first cable interface 20, a second cable interface 22, a third cable interface 24, and a connecting circuit 30.
The first cable interface 20, second cable interface 22 and third cable interface 24 are configured to be connectable with a cable comprising at least two conductors. The connector device illustrated in FIG. 2 is configured for a daisy chain network conforming to the RS-485 standard where each conductor is a twisted pair of copper wires and therefore each cable interface is shown as having four connections.
The connecting circuit 30 operably connects the conductors of the cables connected to the cable interfaces in such a manner that the daisy chain configuration of the network is maintained. For the embodiment of the connector device as shown in FIG. 2, the connecting circuit 30 operably connects the first wire pair of a cable connected at conductor connectors 21A of the first cable interface 20 of the connector device 10 to the first wire pair of another cable connected to conductor connectors 23A of the second cable interface 22 of the connector device 10. The second wire pair of a cable connected to conductor connectors 21B of the first cable interface 20 of the connector device 10 will be operably connected by the connecting circuit 30 to the second wire pair of another cable connected to the conductor connectors 25B of the third cable interface 24. Finally, the connecting circuit 30 operably connects the second wire pair of a cable connected to conductor connectors 23B of the second cable interface 22 of the connector device 10 to the first wire pair of a cable connected to a conductor connector 25A of the third cable interface 24.
FIG. 3 a illustrates a second embodiment of a connector device 10 of the present invention. This connector device 10 is similar to the connector device 10 in FIG. 2 in that it will cause network devices 120 connected to the connector device 10 to be operably connected together in daisy chain configuration, except the connecting circuit 30 operably connects the conductors of network cables connected to the connector device 10 in a different way. In FIG. 3 a, the connecting circuit 30 operably connects the first wire pair of a cable connected at conductor connectors 21A of the first cable interface 20 of the connector device 10 to the first wire pair of another cable connected to conductor connectors 23A of the second cable interface 22 of the connector device 10. The second wire pair of a cable connected to conductor connectors 21B of the first cable interface 20 of the connector device 10 will be operably connected by the connecting circuit 30 to the first wire pair of another cable connected to the conductor connectors 25A of the third cable interface 24. The connecting circuit 30 operably connects the second pair of a cable connected to conductor connectors 23B of the second cable interface 22 of the connector device 10 to the second wire pair of a cable connected to conductor connectors 25B of the third cable interface 24. FIGS. 3 b through 3 g illustrate further embodiments of connector devices with alternate connecting circuits in accordance with the present invention.
FIG. 4 illustrates a connector device 310 that allows the connection of four network devices to the connector device 310. Cable interfaces 20, 22, 24 and 26 are connected together sequentially by connecting circuit 330. The first cable interface 20 has one conductor connector 21A connected to a conductor connector 23A of a next cable interface 22 (connector device 310 as illustrated is configured for a network that uses a twisted pair of wires for each conductor so each conductor connector has two physical connections, one for each wire of the twisted pair of wires). The other conductor connector 23B of the next cable interface 22 is connected to a conductor connector 25A of a succeeding cable interface 24. The other conductor connector 25B of the succeeding cable interface 24 is connected to a conductor connector 27A of a subsequent succeeding cable interface 26. The other cable interface connector 27B of the last cable interface 26 is connected to the other conductor connector 21B of the first cable interface 20. In this manner network devices (not shown) connected to the connector device 310 will be maintained in a daisy chain configuration.
It will be readily understood by a person skilled in the art that a connector device could be constructed with any number of cable interfaces in accordance with the present invention. By using the connector device 310 as illustrated in FIG. 4 and adding any number of cable interfaces in the same sequential manner as illustrated in the connector device 310, a connector device with any practical number of cable interfaces for connecting network devices could be constructed. It is also contemplated that while some of the cable interfaces of a connector device could be connected to a cable having at least two conductors, one or more of the cable interfaces of the connector device could be connected to a pair of separate wires connected to a terminal device in a conventional manner.
FIG. 5 illustrates a network 100 in a daisy chain configuration in accordance with the present invention. The network comprises a plurality of cables 115, a plurality of connector devices 110, and a plurality of network devices 120.
The cables 115 comprise a first end and a second end and have at least two conductors. If the cables 115 are for connected network devices 120 that operate in accordance with the RS-485 standard the two conductors will each be a twisted pair of copper wires and if the cable 115 is category 5 cable, the cable will consists of four copper wire pairs.
The connector devices 110 can be the connector devices as illustrated in either FIG. 2 or FIG. 3 a-3 g.
The network devices 120 are network devices that require or allow connection to a daisy chain network, such as devices that can operate using the RS-485 standard. These devices could be any type of device that is useful to network in a daisy chain configuration, i.e. a main controller and a number of input devices or control devices.
Each network device 120 is connected to a connector device 110 by a cable 115. The connector devices 110 are connected by a cable 115 to either a network device 120 or another connector device 110. All of the connector devices 110 are connected to at least one other connector device 110 to form a single network.
Because the cables 115 used have two conductors in each cable 115, instead of running two cables to each device, one from the previous device and the other to the next device, the present invention uses a single cable 115 containing two conductors connected to each network device 120 and the connector device 110 will maintain the devices in a daisy chain configuration.
Some of the protocols using daisy chains, such as RS485, need a resistor at the beginning and end of the network. The network 100 of FIG. 5 would preferably have a resistor 150 to start the network in the first device and a termination resistor 155 would be in the same device so it would not be necessary to plan a last device to hold the resistor. Alternatively the termination resistor 155 could be in the last network device 120 at the end of the network 100.
FIGS. 6 a, 6 b and 6 c illustrates the addition of an additional device 130 to a network 200. FIG. 6 a illustrates a network 200 with three network devices 120. FIG. 6 b illustrates the network 200 with additional device 130 added. FIG. 6 c illustrates network 200 with additional device 130 added in a different way.
In FIG. 6 a, network 200 comprises a first network device 120 a, a second network device 120 b and a third network device 120 c. The first network device 120 a is operably connected to a connector device 110 by a first cable 115 a. The second network device 120 b is operably connected to connector device 110 by a second cable 115 b. The third network device 120 c is operably connected to connector device 110 by a third cable 115 c. The cables 115 a, 115 b, and 115 c each comprise two conductors.
Referring to FIG. 6 a, if connector device 110 is the connector device illustrated in FIG. 1, a signal sent by network device 120 a along the network 200 will pass out of the first network device 120 a through one conductor in the first cable 115 a into the connector device 110. The connector device 110 will pass the signal to one conductor in the second cable 115 b and to the second network device 120 b. From the second network device 120 b, the signal will travel back through the other conductor in the second cable 115 b, back to the connector device 110. From the connector device 110, the signal will then pass down one conductor of the third cable 115 c to the third network device 120 c, and from the third device 120 c back through the other conductor of the third cable 115 c to the connector device 110 and then back through the other conductor of cable 115 a to the first network device 120 a, where the terminating resistor is placed.
FIG. 6 b illustrates network 200 where additional network device 130 has been added to network 200. To add the additional network device 130 to network 200 as shown illustrated in FIG. 6 a, the end of the third cable 115 c, which connected the third network device 120 c to the network 200, is disconnected from connector device 110. One end of an additional network cable 215 is then connected to connector device 110 and the other end of the additional network cable 215 is connected to additional connector device 210. The unconnected end of network cable 110 c is then connected to the additional connector device 210, re-connecting network device 120 c to the network 200. The additional network device 130 is then connected to one end of another additional network cable 215 and the other end the additional cable 215 is connected to the additional connector device 210. In this manner, the additional network device 130 is now connected into network 200.
FIG. 6 c illustrates network 200 with the additional network device 130 added in a different way than illustrated in FIG. 5 b. Additional network device 130 has been added to network 200 as illustrated in FIG. 6 a by disconnecting the second cable 115 b from the connector device 110. One end of an additional network cable 215 is then connected to connector device 110 and the other end of the additional network cable 215 is connected to additional connector device 210. The unconnected end of network cable 115 b is then connected to additional connector device 210, re-connecting network device 120 b to the network 200. The additional network device 130 is then connected to one end of another additional network cable 215 and the other end of the additional network cable 215 is connected to the additional connector device 210. In this manner, the additional network device 130 is now connected into network 200 in a different location then illustrated in FIG. 6 b.
FIG. 7. illustrates a network 300 where connector device 110 has a shorting plug 180 connected to one of the cable interfaces 24 of connector device 110. Two network devices 120 are connected to the connector device 110 by cables 115. One of the cable interfaces 24 of the connector device 110 contains a shorting plug 180 (although FIG. 7 illustrates the shorting plug 180 inserted into cable interface 24, the shorting plug 180 could be inserted in any cable interface of connector device 110). Shorting plug 180 operatively connects one of the conductor connectors 25 a (not shown) of the cable interface 24 to the other conductor connectors 25 b (not shown) of the cable interface 24. With the shorting plug 180, the connector device 110 can connect the two network devices 120 without requiring a third network device. If at a later time, it is desired to add another network device 120 to the network 300. The shorting plug 180 can be removed from the cable interface 24 of the connector device 110 and the new network device 120 (not shown) can be connected to the network 300 with a cable 115 (not shown).
The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous changes and modifications will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all such suitable changes or modifications in structure or operation which may be resorted to are intended to fall within the scope of the claimed invention.

Claims

1. A Y-connector device for connecting a plurality of network devices in a daisy chain network with cables, wherein each cable comprises two conductors, the apparatus comprising:

a first cable interface comprising a pair of conductor connectors, each conductor connector operative to connect one conductor of a connected cable to a connecting circuit;

a second cable interface comprising a pair of conductor connectors, each conductor connector operative to connect one conductor of a connected cable to the connecting circuit;

a third cable interface comprising a pair of conductor connectors, each conductor connector operative to connect one conductor of a connected cable to the connecting circuit;

wherein the connecting circuit is configured such that:

one of the conductor connectors of the first cable interface is connected to one of the conductor connectors of the second cable interface;

the other of the conductor connectors of the second cable interface is connected to one of the conductor connectors of the third cable interface; and

the other of the conductor connectors of the third cable interface is connected to the other of the conductor connectors of the first cable interface.

2. The Y-connector device of claim 1 wherein each conductor connector of each cable interface is operative to connect to a conductor that is a twisted wire Pair.

3. The Y-connector device of claim 2 wherein each cable interface is operative to connect to a category 5 cable.

4. A daisy chain network comprising at least one Y-connector device according to claim 1, and at least three network devices, wherein:

each network device is operative to communicate as a node in a daisy chain network,

each network device is operatively connected by a cable to a cable interface of a Y-connector device;

wherein each cable interface of each Y-connector device is connected by a cable to one of a network device and another Y-connector device.

5. A daisy chain network comprising at least one Y-connector device according to claim 1, and at least three network devices, and a shorting plug operative to connect to a cable interface such that one conductor connector of the cable interface is connected to the other conductor connector of the cable interface, and wherein:

wherein each cable interface of each Y-connector device is connected to one of shorting plug, a cable connected to a network device, and a cable connected to a another Y-connector device.

6. The system of claim 4 wherein the network devices are operative to communicate on a daisy chain network using the RS-485 standard.

7. The system of claim 4 wherein the first network device in the network comprises a termination resistor for the daisy chained network.

8. The system of claim 4 wherein the last network device in the network comprises a termination resistor for the daisy chained network.

9. A connector device for connecting a plurality of network devices in a daisy chain network with cables, wherein at least one of the cables comprises two conductors, the apparatus comprising:

a plurality of sequential cable interfaces including a first cable interface and a last cable interface, each cable interface comprising a pair of conductor connectors, each conductor connector operative to connect one conductor of a connected cable to a connecting circuit;

wherein the connecting circuit is configured such that:

one of the conductor connectors of the first cable interface is connected to one of the conductor connectors of a next cable interface and the other of the conductor connectors of the next cable interface is connected to one of the conductor connectors of a succeeding cable interface, and conductor connectors of the subsequent succeeding cable interfaces are connected sequentially in the same manner; and

the other of the conductor connectors of the last cable interface is connected to the other of the conductor connectors of the first cable interface.

10. The connector device of claim 9 wherein each conductor connector of each cable interface is operative to connect to a conductor that is a twisted wire pair.

11. The connector device of claim 9 wherein at least one of the cable interfaces is operative to connect to a category 5 cable.

12. A daisy chain network comprising at least one connector device according to claim 9, and at least three network devices, wherein:

each network device is operatively connected by a cable to a cable interface of a connector device;

wherein each cable interface of each connector device is connected by a cable to one of a network device and another connector device.

13. A daisy chain network comprising at least one connector device according to claim 9, and at least three network devices, and a shorting plug operative to connect to a cable interface such that one conductor connector of the cable interface is connected to the other conductor connector of the cable interface, and wherein:

wherein each cable interface of each connector device is connected to one of shorting plug, a cable connected to a network device, and a cable connected to a another connector device.

14. The system of claim 12 wherein the network devices are operative to communicate on a daisy chain network using the RS-485 standard.

15. The system of claim 12 wherein the first network device in the network comprises a termination resistor for the daisy chained network.

16. The system of claim 12 wherein the last network device in the network comprises a termination resistor for the daisy chained network

17. A system to create a daisy chain network comprising:

a plurality of cables, each cable having a first end and a second end and comprising at least two conductors;

at least one connector device comprising:

a first cable interface operatively and connected to a first cable;

a second cable interface operatively connected to a second cable; and

a third cable interface operatively connected to a third cable;

wherein the connector device will maintain devices connected to it in a daisy chain configuration;

at least three network devices each network device operative to communicate as a node in a daisy chain network and each of the network devices operatively connected by a cable to a cable interface of a connector device;

18. The system of claim 17 wherein the conductors are a twisted wire pair.

19. The system of claim 17 wherein the cables are category 5 cables.

20. The system of claim 17 wherein the network devices are configured to operate on a network using the RS 485 standard.

21. The system of claim 17 wherein the first network device comprises a termination resistor.

22. The system of claim 17 wherein the last network device comprises a termination resistor.

23. The system of claim 17 wherein the at least one connector device comprises a connecting circuit operatively connected to the cable interfaces wherein the connecting circuit connects:

one of the conductors of the first cable to one of the conductors of the second cable;

the other conductor of the first cable to one of the conductors of the third cable; and

the other conductor of the second cable to the other conductor of the third cable.

24. A daisy chain network comprising:

first, second, and third network devices each operative to communicate as a node in the daisy chain network, and each comprising an interface connectable to the daisy chain network; and

a plurality of cables, each comprising at least two conductors;

wherein the cable interface of each network device is connected to a single cable; and the cables are connected to form the daisy chain network.