SoftwareJanitor
Member
Sorry for these basic questions. I'm a traditional structured text programmer who's been asked to take over the PLC and HMI coding here and I'm not familiar with the idiosyncrasies of these platforms.
1.) Of course, the Wonderware/Intouch (version 10) app writes to a button tag to change the Operating Mode, but I cannot find the full path to this tag in the InTouch app. I'm expecting to see something like I see in the PI definition [PLC20F]:OP_MODE, but all I can find is an "Access Name" for "PLC20F" which specifies a "Topic Name" of "RSLINX_PLC20F". Where's the connection made to the "OP_MODE" tag? Is that only in RSLINX (to maintain separation of church and state)?
2.) If Wonderware AND the PLC are *both* writing to this same "OP_MODE" tag, how do I know in the logic if Wonderware has modified the "OP_MODE" value in the middle of a scan (or can this not happen)? And if I want to detect when the Operator changes the mode (because the logic can also change it due to failures), then - since this thing is constantly scanning, I have to add logic to trap that out?
Wish these things were more event-driven, as in: press button on HMI, get entrance to a registered thread in PLC logic (instead of scanning everything all the time).
Or am I misunderstanding these things ...???
1.) Of course, the Wonderware/Intouch (version 10) app writes to a button tag to change the Operating Mode, but I cannot find the full path to this tag in the InTouch app. I'm expecting to see something like I see in the PI definition [PLC20F]:OP_MODE, but all I can find is an "Access Name" for "PLC20F" which specifies a "Topic Name" of "RSLINX_PLC20F". Where's the connection made to the "OP_MODE" tag? Is that only in RSLINX (to maintain separation of church and state)?
2.) If Wonderware AND the PLC are *both* writing to this same "OP_MODE" tag, how do I know in the logic if Wonderware has modified the "OP_MODE" value in the middle of a scan (or can this not happen)? And if I want to detect when the Operator changes the mode (because the logic can also change it due to failures), then - since this thing is constantly scanning, I have to add logic to trap that out?
Wish these things were more event-driven, as in: press button on HMI, get entrance to a registered thread in PLC logic (instead of scanning everything all the time).
Or am I misunderstanding these things ...???