Serial Ports
EPM-19 Hardware Reference Manual
34
COM3/COM4 Hardware Configuration
Jumper block V1[1-2] enables the RS-422/485 termination resistor for COM3. Jumper V1[3-4]
enables the RS-422/485 termination resistor for COM4. 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 15: COM3/COM4 Termination Jumpers
Jumper
Position
Function
Jumper In
Jumper Out
1-2
COM3 Rx End-point Termination
RS422/485 (
Note
)
RS-232 (default)
3-4
COM4 Rx End-point Termination
RS422/485 (
Note
)
RS-232 (default)
Note:
RS-485 non-endpoints do not require termination. If receivers are mid-line, remove this termination jumper.
Figure 20. COM3/COM4 End-point Termination Jumpers