
Serial Ports
EPM-31 Hardware Reference Manual
45
COM1/COM2 Hardware Configuration
Jumper block V1[1-2] enables the RS-422/485 termination resistor for COM1. Jumper V1[3-4]
enables the RS-422/485 termination resistor for COM2. The termination resistor should be
enabled for an RS-422 or RS-485 endpoint station; it should be disabled for RS-232 and RS-485
non-endpoint receivers.
Table 11: COM3/COM4 Termination Jumpers
Jumper
Position
Function
Jumper In
Jumper Out
1-2
COM1 Rx Termination
RS-485/RS-422 (
Note
)
RS-232 (default)
3-4
COM2 Rx Termination
RS-485/RS-422 (
Note
)
RS-232 (default)
Note:
RS-485 non-endpoints do not require termination. If receivers are mid-line, remove this termination jumper.
Figure 21. COM1/COM2 End-point Termination Jumpers