Properties Of The Rs422/485 Interface - Siemens SIMATIC ET 200SP Equipment Manual

Product overview
2.3 Properties of the interfaces
2.3.2

Properties of the RS422/485 interface

Definition
The RS422/485 (X27) interface is a differential voltage interface for serial data transmission.
Properties
The RS422/485 (X27) interface has the following properties and meets the following
requirements:
Type
BaseUnit terminals
RS422 signals
RS485 signals
Max. data transmission
rate
Max. cable length
Standard
18
Differential voltage interface
Terminals connected to the electronics module (see RS422/485 interface of
the communications module (Page 23) for assignment)
T (A), R (A), T (B), R (B), GND;
all signals are isolated against the backplane bus and the load voltage
R/T (A), R/T (B), GND;
all signals isolated against backplane bus and load voltage
250 kbps
1200 m for 0.3...19.2 kbps,
500 m for 38.4 kbps,
350 m for 76.8 kbps,
250 m for 115.2 kbps,
200 m for 250 kbps;
cable type LIYCY 3 x 2 x 0.14. T(A)/T(B) and R(A)/R(B) twisted in pairs
To ensure interference-free operation for cable lengths > 50 m, you must
install a terminating resistor of approx. 330 Ω at the receiver end.
DIN 66259 Parts 1 and 3, EIA-RS422/485, CCITT V.11
CM PtP communications module (6ES7137-6AA01-0BA0)
Equipment Manual, 03/2021, A5E03790792-01