C
Hi all
Here is where we have to pin some things down.
We have a map in memory. We have processes that will use the map. As I recall there were at least three approaches and probably more. I got really confused the last time when we got to this part.
1. My original approach was to have a cyclic I/O process that would run the drivers to scan the inputs. set a flag to tell the solver to run and
wait for a flag saying that the solver was done, then run the drivers to set the outputs. Repeat.
2. Have a manager that owns the map and coordinate with semaphores. I'm not sure of the sequencing here because there was so much discussion it was mind boggling. Some one please fill this in.
3. An asynchronous model that reads inputs and sets outputs as they are encountered in the application. This was from someone with strong
experience with *nix distributed control.
4. ?
For a bare bones start, I think 3 doesn't resemble a PLC, but might resemble what Ken etal. do with a state machine. I could be wrong, I haven't seen it.
I think 2 was to solve some problems with 1 and add features, I didn't get whether the mm ran the whole shebang or responded to requests from the solver and an I/O manager. I think both ways were proposed.
I'm leaning towards as simple as possible either 1 or having an overall loop that calls things in sequence. I don't have any code here yet. I have looped a driver to read to the map or write from the map, watching what happened with the map display. Will this work ?
Regards
cww
_______________________________________________
LinuxPLC mailing list
[email protected]
http://linuxplc.org/mailman/listinfo/linuxplc
Here is where we have to pin some things down.
We have a map in memory. We have processes that will use the map. As I recall there were at least three approaches and probably more. I got really confused the last time when we got to this part.
1. My original approach was to have a cyclic I/O process that would run the drivers to scan the inputs. set a flag to tell the solver to run and
wait for a flag saying that the solver was done, then run the drivers to set the outputs. Repeat.
2. Have a manager that owns the map and coordinate with semaphores. I'm not sure of the sequencing here because there was so much discussion it was mind boggling. Some one please fill this in.
3. An asynchronous model that reads inputs and sets outputs as they are encountered in the application. This was from someone with strong
experience with *nix distributed control.
4. ?
For a bare bones start, I think 3 doesn't resemble a PLC, but might resemble what Ken etal. do with a state machine. I could be wrong, I haven't seen it.
I think 2 was to solve some problems with 1 and add features, I didn't get whether the mm ran the whole shebang or responded to requests from the solver and an I/O manager. I think both ways were proposed.
I'm leaning towards as simple as possible either 1 or having an overall loop that calls things in sequence. I don't have any code here yet. I have looped a driver to read to the map or write from the map, watching what happened with the map display. Will this work ?
Regards
cww
_______________________________________________
LinuxPLC mailing list
[email protected]
http://linuxplc.org/mailman/listinfo/linuxplc