Typically we interlock on an HOA if it's in "HAND" with a hardcoded discrete input value, however we decided to change that so when in "HAND", the motor faceplate buttons become enabled/disable instead of start/stop. This is so to prevent someone in the field from starting the motor locally when field guy turns the HOA into "HAND" position if there is an active interlock present at the DCS. So in a sense, if the HOA is in "HAND", someone at the control room will have to "ENABLE" the motor to energize the contact. Basically the "ENABLE" and "DISABLE" functions the same as the "Start"/"Stop".
I am having some difficulty to edit the default named set of mtr2-sp to 0 - stop, 1- run, 2-enable, 3-disabled. I tried to create a custom Named Set but the DC1 block does not take it. Before I go and butcher the default faceplate buttons with a backdoor way, anyone have an idea how to do change the DC1 block into an "ENABLE"/"DISABLE" if HOA is in "HAND"?
In reply to Matt Stoner:
Thanks Matt, I created a custom Named Set to use only 3 states and the DC block can see it now, I think you are right in a sense where the Disable and Stop is the same thing, so I made it 0-Stop, 1-start,2-Enable, 255-undefined, and I was able to see it with the DC block, but it still cannot see the dropdown for "enabled" as an option.
What i'm trying to do is this:
-Start/Stop normally when in "AUTO" from DCS
-Enable/Stop when in "HAND" from DCS.
-Interlock will prevent DC block to energize regardless what position the HOA is in.
Currently I added separate DI block to test the HOA, and eventually it will go into "IN_IO_2" and I changed the State Mask. Honestly the State masks still confuses me sometimes.
Basically the Enable is the "Start" when it is in "HAND". The reason we want to do this is to protect personnel in the field from starting the motor right away when they turn HOA to "HAND" position. In the past we used the HOA signal as an interlock condition, but I am trying to find a more elegant way.
I see that the default faceplate has a visibility on 3 buttons based on "ps_num_selection". I changed the state mask to use Active 2, but did didn't change the faceplate. Is there a parameter that controls the "ps_num_selection"?
In reply to JackC:
Need to make sure that the Enable has the Operator Selectable enabled on your named set.
I only see one output, are you only able to field start the motor?
On the State mask, An empty white box means you are expecting a 0 on that associated input/output for that state. A check box means that you are expecting a 1 and a black box means that you don't care if the signal is a 1 or 0. The problem you will run into is your Enable state which has both inputs as don't care which means that regardless if the motor is running or not, your PV will be Enabled which will be confusing to your operators most likely.
This is quick example of configuration that we see/use for what I think you are trying to do (I DI for Stop/Run on DC1/F_IN_D1, 1 DI for Local/Auto on LOCAL DI block, 1 DO for Stop/Start Enab on START_ENAB external reference parameter)
Just giving you an example that might help with what you are doing. If you have Permissive only conditions configured then you would need some more logic to go into the AND block to cover those in my example.