APPENDIX C COMMUNICATION VARIABLES
General
The product is fitted with the Modbus communication protocol and can be equipped with various
physical interfaces like RS485 and RS232 (please see device datasheet for available options).
The tables below show the various variables that can be accessed through the communication.
Currently, the function codes supported are:
• (4x references);
•
The table below shows the Modbus PDU addresses in a decimal format, followed by its hexadecimal
representation (0x0000). When the PLC address range is required (4x references are typically used
by PLCs), please add a value of 40001 to the Modbus PDU address. E.g. reading the serial number
of the product with PLC-based addressing means: 165 + 40001 = register 40166.
The variables that consist of a multiple register must always read/write in 1 single action!
For this example it is assumed that the variable accumulated total has 3 registers (words) with
address 566, 567 and 568. When a transmission is done, register 566, which acts as the MSW,
arrives first with bit 15 which is the MSB of the lowest addressed word, but is also the MSB (bit 47)
of the complete variable that represents the Accumulated total.
Although most Modbus Masters will support variables that span 2 registers, variables spanning more
registers sometimes require you to manually calculate the resulting value.
For additional information regarding using your Modbus device, please read our General Modbus
or your distributor.
Runtime variables
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