Reading and Writing in the ACE PLC with Modbus
We will see how to read in ACE PLC a Bit and Word in Modbus via the ACE USB port with a Windows Modbus software
Creating a small test program to automatically change the bit and word
Add these MyBit and MyWord tags in ACE Modbus register, then, upload and run the ACE program
Close the vBuilder software, otherwise the COM port will be busy.
Read with Modbus Doctor software (Master Modbus)
Download Modbus Doctor and run it In Windows Device Manager, search the COM port number of your ACE PLC
Select the right COM port and RTU protocol in Modbus Doctor
Select Slave 1, Register 0, Lenght 1 and Type 3 Holding registers for read the Word
Select Slave 1, Register 0, Lenght 1 and Type 1 Coil status for read the Bit
Write in ACE PLC
to do this, you must allow writing in vBuilder by checking the “Remote Writable” function
Then, you can write inside the ACE PLC in Modbus
Note: We have 256 byte transmit and receive buffers. A message longer than 256 byte could be received and clobber some variable that is critical
Modbus-TCP via the ACE-GTW Modbus Gateway
The operation is the same, just select Modbus-TCP instead of Modbus RTU in Modbus-Doctor.