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Communication Wiring
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BASIC I/O Hardware User ManualChapter 2b - Communication WiringBIO4, BIO8 and BIO16 (not AD) Products |
COMMUNICATION WIRING
The Host-to-First BASIC I/O can be RS-422 or RS-485. Most Host computers come aquipped with an RS-232 serial port. A choice must be made to either equip the Host with an RS-422 or RS-485 card, or use an external RS-232 to RS-422/485 converter.
For ranges less than 5000 feet, both RS-422 and RS-485 networks can operate in multidrop mode. For ranges greater than 5000 feet, RS-422 (not RS-485) networks can operate in the Repeat mode. In this mode, the distance between individual units can be up to 5000 feet. The trade-off for using the Repeat mode is that the powering down of any single unit disables communication with all units further "downstream" from the Host.
A network of BASIC I/Os must be made up of units which are configured as either ALL multidrop or ALL repeat.
Network Load vs Noise Suppression:
In order to improve RS-485 Bus noise immunity, particularly under tri-state conditions, a pair of "Network Bias Resistors" have been installed in each BASIC I/O unit. This design feature has been implemented in order to satisfy the majority of our customers. If it is necessary to multidrop more than eight BASIC I/O units (but ultimately less than 32 devices), it will be necessary to remove these network bias resistors so as not to exceed the maximum bus loading. However, in order to retain noise immunity, the network bias resistors should remain installed in at least one BASIC I/O on the network. Figure 2-3 below shows the location of the four network bias resistors.
Figure 2-4 Network Bias Resistor Locations
Figure 2-5 RS-422 Host-To-BASIC I/O Wiring
Figure 2-5 shows two individually shielded twisted pairs of AWG 24. Each pair has a drain wire connected to it's shield. These drain wires are then connected to the signal grounds at each unit. A separate shield encases the entire cable. The drain wire for this over-all shield is tied to earth ground at one location. An example of acceptable wire for this application would be Belden 8162. In a perfect world with no electrical noise and equal ground potentials everywhere, the ground connection is not required; however, omitting this signal ground in industrial applications can lead to costly debugging.
These connections are made by placing a 1/4 inch stripped wire into the openings of the wire clamp terminal block and tightening the screw. This terminal block will accept wire gauges from 14 AWG to 30 AWG.
An alternative means for network connection is to use the 10-pin male connector located behind the clamp terminal block. This connector mates with Molex shell, number 50-57-9005, and uses pins, 16-02-0103. In addition to the Host-to-BASIC I/O wiring, the installer should confirm that the Network Type switches are set in the correct position: Multidrop, Repeater, or Last Unit.
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Figure 2-6 RS-422 BASIC I/O-to-BASIC I/O Multidrop
Figure 2-6 shows two individually shielded twisted pairs of AWG 24. Each pair has a drain wire connected to it's shield. These drain wires are then connected to the signal grounds at each unit. A separate shield encases the entire cable. The drain wire for the over-all shield is tied to earth ground at one end. An example of acceptable wire for this application would be Belden 8162. In a perfect world with no electrical noise and equal ground potentials everywhere, the ground connection is not required. Omitting this signal ground in industrial applications can lead to costly debugging.
These connections are made by placing a 1/4 inch stripped wire into the openings of the wire clamp terminal block and tightening the screw. This terminal block will accept wire gauges from 14 AWG to 30 AWG.
An alternative means for network connection is to use the 10-pin male connector located behind the clamp terminal block. This connector mates with Molex shell, number 50-57-9005, and uses pins, 16-02-0103.
In addition to the BASIC I/O to BASIC I/O wiring, the installer should confirm that the Network Type switches are set in the correct position: Multidrop, Repeater, or Last Unit.
NOTE: The number of BASIC I/Os that can be networked in a Multidrop configuration before a signal amplifier (an external repeater) is needed depends greatly upon external factors. Repeater networks are unlimited.
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Figure 2-7 RS-485 Host-To-BASIC I/O
Figure 2-7 shows one individually shielded twisted pair of AWG 24. There is a drain wire connected to it's shield. This drain wire is then connected to the signal grounds at each unit. A separate shield encases the entire cable. The drain wire for the over-all shield is tied to earth ground at one end. An example of acceptable wire for this application would be Belden 8162 (using only one of the two twisted pairs). In a perfect world with no electrical noise and equal ground potentials everywhere, the ground connection is not required. However, omitting this signal ground in an industrial application can lead to costly debugging.
These connections are made by placing a 1/4 inch stripped wire into the openings of the wire clamp terminal block and tightening the screw. This terminal block will accept wire gauges from 14 AWG to 30 AWG.
An alternative means for network connection is to use the 10-pin male connector located behind the clamp terminal block. This connector mates with Molex shell, number 50-57-9005, and uses pins, 16-02-0103.
In addition to the Host-to-BASIC I/O wiring, the installer should confirm that the Network Type switches are set in the correct position: Multidrop, or Last Unit.
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Figure 2-8 RS-485 BASIC I/O-To-BASIC I/O Multidrop:
Figure 2-8 shows one individually shielded twisted pair of AWG 24. This pair has a drain wire connected to it's shield. this drain wire is then connected to the signal grounds at each unit. A separate shield encases the entire cable. The drain wire for the over-all shield is tied to earth ground at one end. An example of acceptable wire for this application would be Belden 8162 (using only one of the two twisted pairs). In a perfect world with no electrical noise and equal ground potentials everywhere, the ground connection is not required. However, omitting this signal ground in an industrial application can lead to costly debugging.
These connections are made by placing a 1/4 inch stripped wire into the openings of the wire clamp terminal block and tightening the screw. This terminal block will accept wire gauges from 14 AWG to 30 AWG.
An alternative means for network connection is to use the 10-pin male connector located behind the clamp terminal block. This connector mates with Molex shell, number 50-57-9005, and uses pins, 16-02-0103.
In addition to the BASIC I/O-to-BASIC I/O wiring, the installer should confirm that the Network Type switches are set in the correct position: Multidrop or Last Unit.
The number of BASIC I/Os that can be networked in a Multidrop configuration before a signal amplifier (an external repeater) is needed depends greatly upon external factors. Repeater networks are unlimited.
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