ABB RELION REX640 - 3.2.11 RS-485 bias and termination settings; 3.2.12 Serial link diagnostics and monitoring

3.2.11 RS-485 bias and termination settings
A 6 x DIP switch is located on the COM1004...COM1005 cards. The COM card
needs to be pulled out from the relay case to access the switch. See Figure 18
for the location of the switch. RS-485 biasing and termination settings are possible
through this switch. If the switch is in “OFF” position, bias and termination are
disabled and in “ON” position, they are enabled.
ON
OFF
Figure 18: DIP switches on the COM1004...COM1005 cards
Table 40: Bias and termination DIP switch
Switch Signal X8 pin Type
1 RS485_A1/+ 8 Bias
2 RS485_A1/+
RS485_B1/-
Bus termination
3 RS485_B1/- 7 Bias
4 RS485_A2/+ 10 Bias
5 RS485_A2/+
RS485_B2/-
Bus termination
6 RS485_B2/- 9 Bias
1MRS759142 F Basic functions
REX640
Technical Manual
93