Rockwell Automation 937CU-AISTR-DC1 Strain Gauge Converter Installation Instructions - Manual (Page 40)

RS
485 interface
The
Strain Gauge Converter can be connected to an RS 485 2-wire bus via the terminals 19 ... 21 or
via the Power Rail. In principle, such a bus is structured as follows:
Characteristics of the RS
485 interface of the Strain Gauge Converter:
• Baud rate 9600
• 1 start bit, 8 data bits, no parity bit, 1 stop bit
Ensure that the polarity of the connection is correct!
An incorrect polarity causes inverted data signals and thus prevents the bus from
working properly.
+ 5 V
390
Ω
220
Ω
390
Ω
B line/+
A line/-
220
Ω
Strain Gauge
Converter
RS 485 device (up to 31 RS 485 devices)
Bus cable 500 m max.
Connection cable 5 m max.
Connection cable 5 m max.
19
21
Attention
Bul. 937
C Strain Gauge Converter Installation Instructions
38