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My current project revolves around connecting to an existing plc system and retrieving data for research from it. I would appreciate any help on how to make visual basic to 'cooperate'
Ok, before going into the details, let me summarize the system speicifications.
I am using visual basic 6, and the target PLC is LG, having a GM6 application inside. I am connecting with MPI (RS232) and have no chances for hardware upgrade (I requested ModBus but the module request was rejected).
The good thing is that the memory this PLC uses is divided into segments of 16 bits, without the fussy logic of Siemens' PLCs. Also, I get to read mostly booleans and a few integers (no DINTS, SINTS etc).
Now, I have the plc connected to COM1 of my pc, the program is running in the PLC, the GMWIN monitors the program and all is fine.
The question is: how can I make visual basic to read and write in the plc memory? I get to poll the pc for 72 booleans each 5-6 secs, 2 ints each 0.1 sec, and 6 ints each 10-12 secs. Take in mind that I am a programmer but I know next to nothing about PLCs.
I deducted that I need a VB control to take care of this, but everything I found on the net was about ModBus.
Ok, before going into the details, let me summarize the system speicifications.
I am using visual basic 6, and the target PLC is LG, having a GM6 application inside. I am connecting with MPI (RS232) and have no chances for hardware upgrade (I requested ModBus but the module request was rejected).
The good thing is that the memory this PLC uses is divided into segments of 16 bits, without the fussy logic of Siemens' PLCs. Also, I get to read mostly booleans and a few integers (no DINTS, SINTS etc).
Now, I have the plc connected to COM1 of my pc, the program is running in the PLC, the GMWIN monitors the program and all is fine.
The question is: how can I make visual basic to read and write in the plc memory? I get to poll the pc for 72 booleans each 5-6 secs, 2 ints each 0.1 sec, and 6 ints each 10-12 secs. Take in mind that I am a programmer but I know next to nothing about PLCs.
I deducted that I need a VB control to take care of this, but everything I found on the net was about ModBus.