User manual

IEC61131 User and Reference Manual
April 22, 2008
592
Modbus Addressing
Modbus addressing can be used in ISaGRAF program functions.
The C functions dbase and setdbase support Modbus addressing. When the specified port
is configured for one of the Modbus protocols, the function master_message uses Modbus
addressing.
Modbus addresses coil registers with a single bit address ranging from 00001 to 09999.
Status registers are also addressed with single bit addresses ranging from 10001 to 19999.
Input registers are addressed with 16-bit addresses in the range 30001 to 39999. And
holding registers are addressed with a 16-bit address in the range 40001 to 49999.