VAF instruments 667 - 6.11 MODBUS OUTPUT TO EXTERNAL SYSTEM

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6.11 MODBUS OUTPUT TO EXTERNAL SYSTEM
If applicable the PEM4 + SPU3 system can be connected to an external system like an Alarm and
Monitoring System (AMS) or SPU3 Datalogger software through the J3 Modbus slave output, which is at
the processor module in the SPU3 cabinet.
COM-port settings for reading out the J3 Modbus signal at SPU3
Communication protocol
Modbus RTU
Serial interface
RS485 (2-wire)
Baud rate
57600
Data bits
8
Parity
None
Stop bits
1
Flow control
None
Function code
3 (Holding registers)
Modbus slave address
1
The Modbus output data is made available at two 16 bits integers which will have to be converted to 32
bits float according IEEE754. IEEE754 is a standard for binary floating point arithmetic.
Modbus address list
To receive a full list containing the available standard SPU3 Modbus addresses (ASL-668
SPU3 Modbus registers list) or in case your AMS system is programmed for 16 or 32 bit
integer input signals, please contact VAF Instruments for additional information.
In case more than one (1) SPU3 is connected in the same MODBUS-loop, the slave
addresses of these SPU3’s are factory set resp. slave-“1”, slave-“2”, etc.