PD6830X Explosion-Proof Modbus Scanners
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 two Modbus enabled flowmeters connected to a SCADA system
operated out of a control room. A Modbus PLC polls the data out of the flowmeters. A PD6830-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 units 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
40001, 40002
Data Type
Long Integer (2 registers), Binary, Signed
Byte Order
1234 (big-endian: most significant digits register first)
