My first PLC was a Modicon 584 back in the late 80's. Ladder logic was no problem to utilize. I built a pc pased hmi on a 386 using fortran and assembly. I t was a simple.
1. you opened the serial port as you would a file.
2. you would write a connect string to se commnication parms.
3. if parm set with no problem you write a request string (modbus) for data from the plc.
4 you would read port with a buffer large enough to accomidate data requested.
5. if no errors, I had a snapshot of PLC data in the 386 that I could do anything I wanted to with.
Now I am involved Allen bradley. Once again ladder logic no problem, but HMI is. I have searched and searched for AB data that would give me simular data request protocolls, can't find them. AB says that I must use RSlinx to communicate between plc and pc. Ok. I have researched RSlinx and found the tech. info convoluted, terse and unhelp full.
What I would like to find is an accurate, concise explaination for RSlinx and how it it fits into the context of plc communication.
Does any one know where I can get such info. I would appreciate if someone could help me.
1. you opened the serial port as you would a file.
2. you would write a connect string to se commnication parms.
3. if parm set with no problem you write a request string (modbus) for data from the plc.
4 you would read port with a buffer large enough to accomidate data requested.
5. if no errors, I had a snapshot of PLC data in the 386 that I could do anything I wanted to with.
Now I am involved Allen bradley. Once again ladder logic no problem, but HMI is. I have searched and searched for AB data that would give me simular data request protocolls, can't find them. AB says that I must use RSlinx to communicate between plc and pc. Ok. I have researched RSlinx and found the tech. info convoluted, terse and unhelp full.
What I would like to find is an accurate, concise explaination for RSlinx and how it it fits into the context of plc communication.
Does any one know where I can get such info. I would appreciate if someone could help me.
