12. Communication Design Examples 12.1 Communication between PLC and Delta VFD-M Series AC Motor Drive (MODRD/MODWR) Control Purpose: z Repeatedly reading the master frequency and output frequency of VFD-M series AC motor drive then store them in D0 and D1 by MODRD instruction. z Repeatedly setting the running direction and running frequency by MODWR instruction. For example, setting the AC motor drive to run forward in 40Hz. Parameter Settings for VFD-M Series AC Motor Drive: Ъ If AC motor drive can not run normally due to improper parameters, users can set P76 = 10 (factory defaults) and then set the parameters according to the above table. Devices: Control Program:
M1002 Set communication format: 9600, 7, E,1l Retain communication setting Set receiving time-out : 100ms Select communication mode: MODBUS ASCII M0 Execute MODRD instruction M1 Execute the first MODWR instruction M2 Execute the second MODWR instruction DVP-PLC Application Examples 12-5 Parameter Set value Explanation P00 03 Master frequency determined by RS485 com port. P01 03 Operation determined by RS-485 com port, keypad STOP is effective. P88 01 Communication address: 01 P89 01 Communication rate: 9600 P92 01 MODBUS ASCII mode, Device Function 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 D10 Set value of the drive running direction. D11 Set value of the drive running frequency. MOV H86 D1120 SET M1120 MOV K100 D1129 RST M1143 LD= C0 K0 LD= C0 K1 LD= C0 K2 LD= C0 K3 RST C0