9 - 8 VM600 networking manual MAVM600-NET/E
Edition 9 - February 2018
MPC4 card
SETTING UP A MODBUS CONNECTION (CPUM SW VERSION 071 OR LATER)
9.4 MPC4 card
In addition to the existing MPC4 functionality (see 8.4.3 Modbus functions supported by the
VM600), CPUM cards running firmware version 071 or later provide additional functionality.
9.4.1 Analog values (registers)
It is possible to scale analog values to 16-bit unsigned values (the U DataType).
See 8.6.3 Analog values (registers) for more information). Scaling is set using the Min:Max
syntax described in 9.2.4 The MAPPING section.
Min is the minimum value corresponding to 0x0000 in the Modbus register and Max is the
maximum corresponding to 0xFFFF in the Modbus register. Values outside the Min:Max
range are clipped to 0x0000 and 0xFFFF, as necessary.
Each channel outputās minimum and maximum values are fully independent of other
minimum and maximum values used by the VM600 system.
9.4.1.1 Reading minimum and maximum values
It is possible to read the minimum and maximum values configured for a channel using
Modbus:
Address:Function=MIN:Address:Function
or
Address:Function=MAX:Address:Function
However, they can only be read as floating point numbers (the F DataType). The following
example helps to illustrate the process.
Example:
Configuration data from the mapping section of a typical configuration file:
...
30003:4:U:ā50.50:250.0=Slot10:AMC8:C4:V
30004:4:F=MAX:30003:4
30006:4:F=MIN:30003:4
...
The first line of this data is analysed in Table 9-7, the second line in Table 9-8 and the third
line in Table 9-9.
Table 9-7: Reading minimum and maximum values example ā first line
Data Syntax Description
30003 Address Modbus address
4 Function Modbus function 04
U DataType 16-bit unsigned data type
ā50.50 Min Minimum FSD
250 Max Maximum FSD
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