Alternating Logic...?

Hey guys, been programming for quite some time, but I need a push in the right direction for some (for lack of a better term) "alternating logic".

Basically, I'm displaying alarms on an HMI. The HMI will read a single integer (we'll call it INT1). So if alarm condition 1 is met, then INT1 = 1, if alarm condition 2 is met then INT = 2, and so on. If I have a single alarm, everything works great.

What I need however, is that if I have conditions 1 and 7 met, that INT1 will bounce back and forth between "1" and "7". If condition 22 is then added, then INT1 will add "22" to its rotation. Then of course, as alarms are cleared, they will drop out of the rotation.

I'm sure there's something on this already, but I couldn't find it b/c I'm not sure what to call it! Anybody done this before and have an example they'd be willing to share?

And FYI, b/c of my particular situation, no, I cannot use the built in alarm function on the HMI that would normally do this for you...gotta do it this way.

Oh yeah...silly me...this is being done in a CompactLogix processor!

http://www.plctalk.net/qanda/attachment.php?attachmentid=34525&d=1416261448

This thread references 13 alternator references and was originally posted by Lancie1.
It has been very useful to me.
Check it out!

Sorry, this is not a thread but a PDF attachment.

Set up your conditions to produce your bits 1 - 15.
No error : errorWord = 0
if errorWord > 0 then cycle through the bits (using a 6 second timer) and set Int1 to whatever bit is set (bit 6; Int1=6)

PLC Pie Guy said:

http://www.plctalk.net/qanda/attachment.php?attachmentid=34525&d=1416261448

This thread references 13 alternator references and was originally posted by Lancie1.
It has been very useful to me.
Check it out!

Sorry, this is not a thread but a PDF attachment.

Click to expand...

I don't think you read my post all the way...That is not what I'm trying to do at all...good information...but not my current dilemma!

That function could be done with Sequencer instructions. For each alarm, a number is added to the sequence using the Sequencer Load (SQL) instruction. The Sequencer Output (SQO) is triggered every X seconds, and it then sends out each alarm, one at a time, for however many is in the stack. You can use a self-resetting timer to rotate the alarms.

You would have to add logic to remove alarms from the sequence. This might be done by using RES (Reset) at the end of the SQO (when DN goes ON) to remove all alarms, then use SQL to reload with the current valid alarms.

Dan's method is much better.

danatomega said:

Set up your conditions to produce your bits 1 - 15.
No error : errorWord = 0
if errorWord > 0 then cycle through the bits (using a 6 second timer) and set Int1 to whatever bit is set (bit 6; Int1=6)

Click to expand...

I see what you're saying...but this is the part that gets me.

So if bit 1 becomes active, then INT1 = 1, if bit 3 becomes active then INT1 = 3....how do I make INT1 = 1 for 6 seconds and then IMMEDIATELY = 3? It would have to ignore the fact that bit 2 is NOT set. And then after 3 is displayed for 6 seconds, it needs to skip 4-15 and IMMEDIATELY come back to bit 1.

I don't want to change INT1 to "3" and then leave it there while I wait 6 seconds for bit 4, 5, 6, etc until I get back around to bit 1. This would cause Alarm 1 to display for 12 seconds, and Alarm 3 to display for 78 seconds.

Or am I misunderstanding you??

Lancie1 said:

That function could be done with Sequencer instructions. For each alarm, a number is added to the sequence using the Sequencer Load (SQL) instruction. The Sequencer Output (SQO) is triggered every X seconds, and it then sends out each alarm, one at a time, for however many is in the stack. You can use a self-resetting timer to rotate the alarms.

You would have to add logic to remove alarms from the sequence. This might be done by using RES (Reset) at the end of the SQO (when DN goes ON) to remove all alarms, then use SQL to reload with the current valid alarms.

Click to expand...

I did consider this...and I also considered loading/unloading a FIFO, but I hated to come up with something so complicated! If I have to, than so be it, but I thought someone might have a simple solution I was just overlooking!

I would say as each alarm gets set, send that alarm number to an array or stack incrementing a counter each time a new alarm gets set, every second or 2 (however long you want each one to be displayed) index to the next array element, use the counter acc to know when to reset back to the first alarm.

Use an ADD instruction to increment the testing pointer to the bit number (indirectly addressed) - this is done each scan if you're not busy displaying an error.
If you're not busy displaying an error, and you find a bit set, seal-in a rung to run the timer and move the bit number into Int1.
When the timer expires, return to indexing (ADDing) away at the bits.

Hmm mine is just the manual way of doing what Lancie said...I do agree though dan does seem to have a better/simpler idea

Atatched is one way of sequencing up to 32 alarms (bits set in a DINT) to a number which is held for a time.

Unzip and import it as a routine.

Heres another way to do it.

Steve

OOps forgot to modify the equals comparisons (cut & paste)

bernie_carlton said:

Atatched is one way of sequencing up to 32 alarms (bits set in a DINT) to a number which is held for a time.

Unzip and import it as a routine.

Click to expand...

Bernie....this is totally genius. Exactly what I was looking for!

Nehpets, I'm sure your way is good too...I just got to Bernie's first! Thanks guys!

bernie_carlton said:

Atatched is one way of sequencing up to 32 alarms (bits set in a DINT) to a number which is held for a time.

Unzip and import it as a routine.

Click to expand...

What is the purpose in doing this?