GE RSTi-EP - Page 214

Chapter 5 Detailed Descriptions of I/O Modules
GFK-2958E RSTi-EP User Manual 210
Connection Cables for the Serial Device
Use shielded cables, because electromagnetic interferences 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
Maximum Cable Length
≤ 2500 pF
15 m (49 ft), shielded
55 pF/m
45 m (147 ft)
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
Maximum Cable Length
≤ 19200
1200 m (3937 ft), shielded
38400
500 m (1640 ft)
57600
250 m (820 ft)
115200
200 m (656 ft)
• RS485: Use one core pair for Data+/Data–. You can use any wire for the ground singal GND
COM. The remaining free wires should be connected to ground.
• RS422: 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 GND COM. The
remaining free wires should be connected to ground.