12. Communication Design Examples 12.2 Communication between PLC and Delta VFD-B Series AC Motor Drive (MODRD/MODWR) Control Purpose: z Repeatedly reading the master frequency and output frequency of VFD-B series AC motor drive by MODRD instruction. z Start AC motor drive in reverse direction when Start is pressed. Increase 1Hz per second until it reaches 50Hz. Maintain the frequency at 50Hz. (MODWR instruction) z Stop AC motor drive by when Stop is pressed. (MODWR instruction) Parameter Settings for VFD-B Series AC Motor Drive:
Ъ If AC motor drive can not run normally due to improper parameters, users can set P00-02 = 10 (factory defaults) and then set the parameters according to the above table. Devices: Control Program: M1002 Set communication format: 19200, 8, N, 2 Retain communication setting Set receiving time-out: 100ms Select communication mode: MODBUS RTU Reset D2 first when PLC runs Reset D10 first when PLC runs DVP-PLC Application Examples 12-8 Parameter Set value Explanation 02-00 04 RS-485 serial communication. Last used frequency saved. 02-01 03 RS-485 serial communication. Keypad STOP/RESET enabled. 09-00 01 Communication address: 01 09-01 02 Communication baud rate: 19200.
09-04 03 MODBUS RTU mode, protocol Device Function X0 Start button for the drive X1 Stop button for the drive M0 Executing MODRD instruction to read master and output frequency M1 Executing the first MODWR instruction to set the running direction M2 Executing the second MODWR instruction to set the running frequency MOV H99 D1120 SET M1120 MOV K100 D1129 SET M1143 RST D2 RST D10