Emerson PACSystems RSTi-EP - 5.21 Digital Pulse Width Modulation Output Module EP-5422

User Manual Section 5
GFK-2958L May 2021
Detailed Description of I/O Modules 259
Connection Cables for the Serial Device
Use shielded cables, because electromagnetic interferences from the surroundings have to
be assumed. The maximum permissible 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 must 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
1,200 m (3,937 ft), shielded
38400
500 m (1,640 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 signal
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 signal
GND COM. The remaining free wires should be connected to ground.