Emerson PACSystems RSTi-EP User Manual page 230

User Manual
GFK-2958J
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
≤ 2500 pF
55 pF/m
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
≤ 19200
38400
57600
115200
•
•
Detailed Description of I/O Modules
Maximum Cable Length
15 m (49 ft), shielded
45 m (147 ft)
Maximum Cable Length
1,200 m (3,937 ft), shielded
500 m (1,640 ft)
250 m (820 ft)
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.
Chapter 5
Oct 2019
215