RICHARD_C2K

When I tried using DB I seemed to get an error on the status and no TX or RX light would flash hence I am using M Thanks Richard

I've changed the DATA_PTR FOR P#M500.0 WORD 100 instead of MD500 as I have been altering the data length to see if I have any response. I have been entering 16#0001 into MW500 and 16#0150 into MW502 Thanks Richard

Hi Here is the MB master when I am monitoring so you can see the values that are being sent to the function. Thanks Richard

Hi Dekor Thanks for the reply. Ive been going through my program and trying different settings and I am getting the TX light to flash on then go off as the RX light briefly flashes on then off but I am not getting a Done signal form MB_MASTER_Done and just keep getting the Busy signal staying on. I assume the transmission then times out and the TX and RX lights are then flashing again in the same sequence. I am not getting any errors from the status. I am also a little confused where the information then get written back to. To try and keep my program simple I am trying to write 1 to register 1 (40001) (I believe this should turn the drive on) and 16#0200 (200Hz) to register 2 (40002). On my MB_Master I have the following Mode = 1 Data Addr = 40001 Data_Len = 2 Data_PTR = MD500 Inside MD500 I have 16#0200_0001 when monitoring the value. any tips or ideas would be appreciated. Thanks Richard

Hi All I am new to Siemens plc (S7-1200) and modbus and I am having a bit of trouble setting a siemens plc to communicate with a VFD (OptiDrive). Are there any walk throughs on how to set this type of communication up and test it. A lot of the examples I have seen have been regarding setting the plc up as a slave but as Ill have just the one PLC and 3 drive units I believe I need to set it up as a Master and teh VFDs will be the slaves. Thanks Richard