MODBUS Slave Configuration Register/Coil write access

This block enables the configuration of register addresses for which the master has writing access. According to the data model “Modbus”, “Coils” and “Holding Register” are supported. Addressing is 0 based.

In the block, up to 8 objects can be indicated. The I/O modules, which are accessible on the hardware, and the freely definable process variables are supported.

This function block is the interface between the variables and the I/Os to the Modbus. The block does not have a processing function. That means, that blocks of this kind have to be called at least once to announce the configuration in the controller before a communication over Modbus can take place. Further calls of the blocks are not necessary, but they also do not have further influence on the application.

The addresses are checked when entering into run mode and additionally when downloading the program onto the controller. If there are any overlaps, they are output as errors and the according blocks are marked (they can be localized with the error browser). A download is only possible when all errors are solved (see also description).


The basic parameters of the slave configuration are assigned over an additional dialog.

The individual objects can be assigned over the parameter dialog (when implementing the block and/or over the context menu, but only in edit mode).

The according data range can be defined over the list box. Thus, all further available data types and/or I/O functions are set. By implementing the number, the according input lines are set. The address assignment is described more closely in chapter „Appoint an address“.


Name I/O Type(s) Function
Data 1-8 O BIT, UCHAR, WORD, LONG, FLOAT or I/O function Specify the sink on which information are written when requested