Modbus Rtu Serial Communications - Siemens SITRANS RD300 Operating Instructions Manual

SITRANS RD300
The meter is capable of accepting any voltage from -10 VDC to +10 VDC.

Modbus RTU Serial Communications

Serial communications connection is made to an RJ45 connector
labeled M-LINK. For interfacing to the RD300, use the 7ML19306AF for
RS-232 or the 7ML19306AG for RS-485. The same port is used for
interfacing with all expansion modules (e.g. external relays, digital I/O).
Relay Connections
Relay connections are made to two six-terminal connectors labeled
RELAY1 – RELAY4. Each relay's C terminal is common only to the
normally open (NO) and normally closed (NC) contacts of the
corresponding relay. The relays' C terminals should not be confused
with the COM (common) terminal of the INPUT SIGNAL connector.
RELAY4
6
NO
A5E31917845
Voltage Input Connections
RELAY3
5 4 3 2
NC C NO NC
Relay Connections
SITRANS RD300 – OPERATING INSTRUCTIONS
RELAY2
1 6 5 4
C NO NC C
RELAY1
3 2 1
NO NC C
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