RS485 wiring
On the controller’s top side, two RS485 ports operate as COM1 and COM2. Each port is capable of up to 115,200 baud, and uses
a three-position screw terminal connector.
Figure 6. RS–485 wiring example
| 1 | This RS485 port A (COM1) could be used to support a trunk of IO-R-16 modules.
NOTE: Do not mix different types of RS485 modules or devices on the same RS485 trunk.
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| 2 | This RS485 port B (COM2) supports a network of other field devices using RS485 communications. |
| 3 | This port links to up to 32 or more devices, depending on device specifications. |
NOTE: RS485 devices on the same network should use the same protocol and baud rate.
Use shielded, twisted-pair, 18-22 AWG cabling to wire in a continuous multidrop fashion to other RS485 devices: minus-to-minus, plus-to-plus, and shield-to-shield. Connect the shield wire to earth ground at one end only, for example, at the controller.