Advanced MODBUS Simulator


Thread Starter

Kiran Kirtane

We want to test a device with PLC program.

With various modbus slave simulator it works fine by simulating the values at the simulator value manually.

However we want automate this testing i.e. when a value is written into a holding register, the same value shall be automatically updated into an input register.

Is there any way to link the holding register value to the input register directly?

For Example,

Assume the modbus slave device is a VSD. PLC writes a Speed reference value into a holding register and reads the actual speed from an input register.

PeakHMI has a MODBUS slave port type (emulates all register types and ranges) and a scripting engine.

We also have a very low cost RLL program that also emulates a MODBUS slave port type (emulates all register types and ranges).

Either program can be used to accomplish the task.

Check out our web site.

Good luck,

Frank O'Gorman

You can do this using one of our programmable Modbus simulators: ModMultiSim ( or ModSlaveSim (

There are two ways of linking an input register to a holding register. You can use the address-mapping facility to overlay the input and holding registers, or you can program the input register to update its value from the holding register. The latter method is more flexible since you can include dependencies on other register values, simulate delayed responses, etc.

Wingpath Software Development