9
3 - HARDWARE DESCRIPTION
3.9 - RS485 wiring (best practice)
For RS485 ports, one of the following cables can be used:
■ For CCN or Modbus communication which is over 300 m or in
a noisy environment with Variable Frequency Drive (VFD),
a cable with two twisted pairs is recommended. For example,
Belden 3106A or Alpha Wire 6454.
■ For applications where the length of the cable is up to 300 m
and there is no Variable Frequency Drive (VFD), it is possible
to use cost-effective cable solutions, for example, Belden 8772.
Note that “+” and “-” are communication signals and they are from
the same twisted pair.
The signal ground could be a single wire or a twisted pair and it should
be connected to the “C” pin of J10 (Modbus RTU) or J7 (CCN).
This wire is required so that all nodes on the bus share a common
ground reference connection.
If a shield is used, then the shield cable should be properly
terminated and connected as short as possible at ONLY ONE
END to one of the following:
■
the chassis ground for the 4.3-inch controller OR
■
the SHD connector pin for the 7-inch controller.
3.9.1 - RS485 wiring: 4.3-inch controller
The following diagrams illustrate possible RS485 wiring schemes
for 4.3-inch controllers.
The first wiring scheme is the best option (RECOMMENDED), but
the second or the third wiring can also be used.
No.1 RS485 wiring diagram (RECOMMENDED)
No. 2 RS485 wiring diagram (CORRECT)
No. 3 RS485 wiring diagram (CORRECT)
No. 4 RS485 wiring diagram (INCORRECT - Do not use!)
No. 5 RS485 wiring diagram (INCORRECT - Do not use!)