User manual
6 Detailed descriptions of I/O modules | Serial communication module UR20-1COM-232-485-422
387Manual u-remote1432790000/08/12.2015
Connection cables for the serial device
Please use shielded cables, because electromagnetic inter-
ferences from the surroundings have to be assumed. The
maximum permissable cable length depends on the cable
capacitance and the baud rate.
Connecting a RS232 device
Maximum cable length RS232
Cable capacitance Max. cable length
≤ 2500pF 15 m (49 ft), shielded
55 pF/m 45 m (147 ft)
Recommended cable type:
LIYCY 0.14mm² or 0.34mm² (e.g. Weidmüller PAC-UNIV-
D9M-F-1M5, Order No.1350400015)
Connecting a RS485 or RS 422 device
The serial device has to be connected using a twisted pair
cable (U/UTP, Type Cat-3 or J-2YY-2x2x0,6).
Maximum cable length RS422/485
Baud rate in kbps Max. cable length
≤ 19200 1200m (3937 ft), shielded
38400 500m (1640 ft)
57600 250m (820 ft)
115200 200m (656 ft)
Recommended cable type for RS422/485:
LIYCY or LiYY, 0,25mm². Both ends of the cable must be
terminated.
▶ RS485: Please use one core pair for Data+/Data–. You
can use any wire for the ground singal GNDCOM. The
remaining free wires should be connected to ground.
▶ RS422: Please connect the wires for transmitting signals
TXD+/TXD– and those for receiving signals RXD+/RXD–
in pairs respectively. You can use any wire for the ground
singal GNDCOM. The remaining free wires should be
connected to ground.