So I create a virtual M580 PLC in unity pro software and I have connected the virtual PLC with OPC client which is installed on another computer.
However for the virtual PLC configuration, I haven't added any I/O modules on the rack, there are only power supply and processor on the rack. I am confused why the connection could be established and my Ladder counter diagram could work (I can actually see the counter increasing at the OPC client side).
So I have few questions, any answers will be appreciated
1. Why this could work without any I/O modules? I didn't set the address (e.g. %MW, %I etc.) for the variables, I just left them empty, and I didn't tick the 'HMI variable' options.
2. If the processor have certain number of I/O points (I check in the viewer that there are 4096/4096 available I/O), and I have 2 output variables, why the total available I/O number doesn't change? (still 4096, but should be 4094?)
Sorry for asking the silly questions, I am a new guy to PLC and sort of lack some level of the knowledges. Thanks in advance for any help!!
However for the virtual PLC configuration, I haven't added any I/O modules on the rack, there are only power supply and processor on the rack. I am confused why the connection could be established and my Ladder counter diagram could work (I can actually see the counter increasing at the OPC client side).
So I have few questions, any answers will be appreciated
1. Why this could work without any I/O modules? I didn't set the address (e.g. %MW, %I etc.) for the variables, I just left them empty, and I didn't tick the 'HMI variable' options.
2. If the processor have certain number of I/O points (I check in the viewer that there are 4096/4096 available I/O), and I have 2 output variables, why the total available I/O number doesn't change? (still 4096, but should be 4094?)
Sorry for asking the silly questions, I am a new guy to PLC and sort of lack some level of the knowledges. Thanks in advance for any help!!