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Online Help icom Data Suite |
Modbus
The icom Data Suite can read out or set registers of connected Modbus devices as Modbus master. Moreover, it may also act as Modbus slave and provide their data points to other Modbus master devices via Modbus.
Modbus master
The icom Data Suite can read out or set registers of connected Modbus devices. Each Modbus device must be entered in the icom Data Suite for this. The registers to be read out or set are then entered as data points for each of the Modbus devices. These are read out in events and set in actions. Depending on the type, they are digital or analogue data points.
For the status indication of connected Modbus Slave devices (in the Status menu on the Current values) page must be observed that Modbus TCP devices are shown as 'online' as soon as the TCP connection has been established, but Modbus RTU devices only, if the serial connection is established and at least one data point has been read successfully, i.e. at least one data point must be configured.
Modbus slave
The icom Data Suite may act as Modbus slave and provide their data points to other Modbus master devices via Modbus. Individual Modbus slaves can be added for this. A series of mappings can be added for each of these Modbus slaves. A data point will be mapped to a Modbus register in each of these mappings. Other Modbus master devices can read or set the data points of the icom Data Suite via the Modbus interface this way.
Modbus registers
The following types are available for the Modbus data points:
| Type | Type | Function code / comment |
|---|---|---|
| Holding register | analogue | FC 03 (read) FC 06 (write) |
| Bit of holding register | digital | allows to monitor (FC 03) and set (FC 06) a single bit of a holding register |
| Coil (outputs) | digital | FC 01 (read) FC 05 (write) |
| Discrete input (inputs) | digital | FC 02 (read) |
| Input register | analogue | FC 04 (read) |
| Bit of input register | digital | allows to monitor (FC 04) a single bit of an input register |
The Modbus data points (holding registers, coils, discrete inputs, input registers) can either be specified decimal or hexadecimal with preceding "0x". Additionally, it is also possible to select or monitor or set single bits of a register value with Bit of holding register or Bit of input register. If values of another format than Unsigned Integer or Signed Integer are read out for Holding register or Input register, several Modbus registers will be read automatically and assembled to the configured format. The byte order of the configured Modbus device must correspond to the hardware for this. If the String format is used for Holding register or Input register, the length specified in the Maximum string length field will be used, to read out the string from multiple Modbus registers and combine it automatically.
In Modbus addressing, a number is assigned to each register. Holding register addresses are often preceded by "4xxxx" or "4xxxxx". Moreover, the first register address is often considered as "1" for some devices. The icom Data Suite does ALWAYS start with "0" for addressing. Depending on the Modbus communication partner used, it may be necessary to use an offset of "-1", "-40000", "-40001", "-400000" or "-400001" for addressing.
When using Modbus RTU, it must be observed that the used serial interface of the router is not used by another application to avoid possible conflicts.