"Best use" for programming alarms

Hello, I have been programming siemens PLCs for 2.5 half years now for industrial solutions, but I have never really found any coherent information on a "Best Case" for how to program alarms on a PLC and integrate them to the Comfort HMI.

My solution to this issue  was to program an FB that moves a Bit sequence of 128 alarms (Array of 128 bools) and a bit sequence of 128 reset bits into an array of 16 words acting like the alarm and reset bits in the HMI.

I feel like this works quite well in practice, but I wanted to see what other people use in their solutions and if there is a "Correct" way of doing alarms or an industry standard or something similar. 

Thanks in advance for the response.

There's the AlarmS library for the Simotion. I got to use it and I liked it a lot because it worked very well with OMAC PackML implementation.

So I ported it to S7-1500 and made it use ProgramAlarm mechanism instead of AlarmS. I'm not sure if it is possible with S7-1200 too.

Thanks for the response.

I will definitely keep the Simotion AlarmS library in mind when I use Simotion hardware. I will check out the possibilities with "ProgramAlarm" on 1500 PLCs.

We use quite a few 1200 PLCs as well in smaller basic projects and was wondering if anyone knows any good concept for Alarm handling in a 1200 CPU. I know that the 1200 series is quite limited on possibilities compared to a 1500 though.

Hati

If i recall right, this same question has been on the table before also. Try using the forum search, it's a powerful tool to get answers

 I am a bit unaware on what to search for to find this. I was not able to find any other posts talking about this when I looked around before posting. But I can try and look some more.

Matthew Hunt

 

Hati

If i recall right, this same question has been on the table before also. Try using the forum search, it's a powerful tool to get answers

 I am a bit unaware on what to search for to find this. I was not able to find any other posts talking about this when I looked around before posting. But I can try and look some more.

 I tested search words: HMI alarms, when i was in Industrial Software on the forum tree. It gives a lot of nice findings.

Configuration of Messages and Alarms in WinCC (TIA Portal)

Hati

 

Matthew Hunt

 

Hati

If i recall right, this same question has been on the table before also. Try using the forum search, it's a powerful tool to get answers

 I am a bit unaware on what to search for to find this. I was not able to find any other posts talking about this when I looked around before posting. But I can try and look some more.

 I tested search words: HMI alarms, when i was in Industrial Software on the forum tree. It gives a lot of nice findings.

Configuration of Messages and Alarms in WinCC (TIA Portal)

 Thank you for the help, but this is not what I am looking for. This document does not really discuss programming alarms in 1200 PLCs, only generating user diagnostics which is not exactly what I am looking for.

It is not possible for me to be certain what you are looking for Matthew, but I think I might understand what it is you are driving at. The problem is that the subject is not that simple. Actually, I am not sure that there is such a thing as a definitive ‘best case’ way of doing it. On this, as with anything else, there will be different opinions and philosophies. And the problem with me offering you any of the code I use is that the way I have alarms working may not be exactly what you want. But I can make a couple of points about the technique that I use. If nothing else, it might generate some discussion that will be helpful for you.

So the key point about the technique I use is that I word handle the alarms. I don’t handle them as individual bits. The reason for that is that, if you have a significant number of alarms and you handle them all individually, you can finish up with some horrendously long program blocks full of essentially the same code repeated for each alarm. I have seen many programs that have exactly that. So I have a function that takes a 16 bit word value and handles the detection, acknowledging, and resetting of individual alarms using masking. Obviously, each detection bit must be coded individually, and depending on how acknowledging works for you, there might be the need to have some access to the individual acknowledgement bits.

I’m thinking that a few screenshots might be the best way to convey what I am talking about. You can, of course, organise your words functionally – so a word of device fault alarms, a word of analogue value out-of-limits alarms, that sort of thing. As you will see, my organisation is by the actual equipment – using the S88 standard concepts of unit modules and equipment modules – if that means anything to you.

KenNatton

It is not possible for me to be certain what you are looking for Matthew, but I think I might understand what it is you are driving at. The problem is that the subject is not that simple. Actually, I am not sure that there is such a thing as a definitive ‘best case’ way of doing it. On this, as with anything else, there will be different opinions and philosophies. And the problem with me offering you any of the code I use is that the way I have alarms working may not be exactly what you want. But I can make a couple of points about the technique that I use. If nothing else, it might generate some discussion that will be helpful for you.

So the key point about the technique I use is that I word handle the alarms. I don’t handle them as individual bits. The reason for that is that, if you have a significant number of alarms and you handle them all individually, you can finish up with some horrendously long program blocks full of essentially the same code repeated for each alarm. I have seen many programs that have exactly that. So I have a function that takes a 16 bit word value and handles the detection, acknowledging, and resetting of individual alarms using masking. Obviously, each detection bit must be coded individually, and depending on how acknowledging works for you, there might be the need to have some access to the individual acknowledgement bits.

I’m thinking that a few screenshots might be the best way to convey what I am talking about. You can, of course, organise your words functionally – so a word of device fault alarms, a word of analogue value out-of-limits alarms, that sort of thing. As you will see, my organisation is by the actual equipment – using the S88 standard concepts of unit modules and equipment modules – if that means anything to you.

 Thank you for the insight! I am looking at various concepts other people use for alarm handling to look for good methods that work well for alarm handling. Thanks a lot for the information.

Good question. I was wondering why there isn't such a std handling available also, at least I couldn't find it.

I'm not using siemens hmi. I searched and tried a lot. Want my simple alarms as bits packed in a word without using merkers or abs addressing ('non-optimized'). Tried a lot, gather/scatter needs full 8/16/32/64 bits. Don't like arrays of bools. Can't get AT construct to do what I want... UDT, oh my...

I'm now setlled on a fb with bools that cpy's to dword-bits  with slice access. Only I' can't define the slice access symbolic. That something so simple can be so complicated, I guess we can't stop 'progess'...

like this:

FUNCTION_BLOCK "Alarm"
VAR
EstopLoadrack : Bool;   // hz1
EstopPumpRoom : Bool;
EstopBlendRoom : Bool;
EstopTankFarm : Bool;
LoadarmValve : Bool;
TankP8Valve : Bool;
Tank2Valve : Bool;
Tank10Valve : Bool;
Tank10HL : Bool;
Tank2HL : Bool;
Pump8RunContact : Bool;
Pump8Trip : Bool;
Pump8WS : Bool;   // work switchs off
....

bits : DWord;   // packed alarm bits for report
END_VAR


BEGIN

IF "HmiWrite".resetalarms
THEN

"HmiWrite".resetalarms := false;
"HmiWrite".LoadoutControl := "Reset";   // loadout delegates reset to the rest...

END_IF;


#EstopLoadrack          := "LoadoutP8".ErrorEStop;
#EstopPumpRoom          := "LoadoutP8".ErrorEStop;
#EstopBlendRoom         := "LoadoutP8".ErrorEStop;
#EstopTankFarm          := "LoadoutP8".ErrorEStop;

#LoadarmValve           := "LoadoutP8".LoadarmValve.Error;
#TankP8Valve            := "LoadoutP8".TankValve.Error;
#Tank2Valve             := "LoadoutP8".T2Valve.Error;
#Tank10Valve            := "LoadoutP8".T10Valve.Error;

#Tank10HL               := "LoadoutP8".Tanks["T10"].ErrorHL;
#Tank2HL                := "LoadoutP8".Tanks["T2"].ErrorHL;
#Pump8RunContact        := "LoadoutP8".Pump.ErrorRunContact;
#Pump8Trip              := "LoadoutP8".Pump.ErrorVfd;
#Pump8WS                := "LoadoutP8".Pump.ErrorWorkSwitchOFF;
....

// gather bits, sigh
#bits.%X0   := #EstopLoadrack;
#bits.%X1   := #EstopPumpRoom;
#bits.%X2   := #EstopBlendRoom;
#bits.%X3   := #LoadarmValve;   // mask 0xF

#bits.%X4   := #TankP8Valve;
#bits.%X5   := #Tank2Valve;
#bits.%X6   := #Tank10Valve;
#bits.%X7   := #Tank10HL;   // not for hmiLG, mask 0x7F

#bits.%X8   := #Pump8RunContact;
#bits.%X9   := #Pump8Trip;
#bits.%X10  := #Pump8WS;
...

#alarmactive := #bits <> 0 OR #barcode OR #NoReleaseNumber OR #NoWeight;

#alarmLGactive := (#bits & 16#1BFC_7F7F) <> 0 OR #barcode OR #NoReleaseNumber OR #NoWeight;


END_FUNCTION_BLOCK