Precision Digital PD6730X - Manual (Page 29)

PD6730X Vantageview Super Snooper Modbus Scanner Instruction Manual
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Example 2: Snooper Displaying Flow Rate from Modbus Flow Meters
In this application we have a system consisting of (2) Modbus enabled flow meters connected to a
SCADA system operated out of a control room. A Modbus PLC polls the data out of the flow meters. A
PD6730-AX0-I-2 has been added to the system as a Modbus Snooper, to provide the operators an easy
to read field display near the flow lines.
The scanner displays one flow rate on the top display, and one on the bottom display. Each has an
alternating tag and unit for clear identification.
Example 2 Flow Meter & PLC Setup, Register Numbers, & Process Variables
Serial Communications
Parameters
Flow Transmitter 1 Flow Transmitter 2 Control Room PLC
Address (Slave ID) 100 200 N/A
Baud Rate 4800 bps 4800 bps 4800 bps
Transmit Delay 50 ms 50 ms 50 ms
Parity None, 1 Stop Bit None, 1 Stop Bit None, 1 Stop Bit
Fixed Serial Data
Parameters
Modbus Flow Meter Data
Flow Data Register 30001, 30002
Data Type Long Integer (2 registers), Binary, Signed
Byte Order 1234 (most significant digit register first)