Can someone here help me figure out some programming. I'm using RSLogix 500 and a SLC5/05 cpu. My water pump fills a tank that is equiped with a ultrasonic level transmitter and this inputs to a 1746-NI8 analog input card, If the pump is energized and if there is no rate of change in my tank for 10 seconds (tank not filling), I want to indicate an alarm... any suggestions? I could probally do it with a bunch of timers and counters and monitor the bits on the analog input, but maybe someone has a better idea.
Pump alarming
- Thread starter DRThorne
- Start date
seppoalanen
Member
Integer table from 0 to 9, Infeed pointer MOD 10, Outread pointer Mod 10 is In-pointer -9 (Mod 10).
Read A-input every second and put it to table where Infeed pointed and increment I-Pointer by 1 (MOD 10). Outread pointer is I-Pointer+10 mod 10. (MOD 10 means when pointer is 10 it must put to 0)
When separate 10 sec Timer from the pump start have done start control data from Outread must be greather than in Infeed when pumping. System controling continuously every second last 9 seconds changes after 10 sec from the start.
Read A-input every second and put it to table where Infeed pointed and increment I-Pointer by 1 (MOD 10). Outread pointer is I-Pointer+10 mod 10. (MOD 10 means when pointer is 10 it must put to 0)
InP 90123456789
Outp 01234567890
When separate 10 sec Timer from the pump start have done start control data from Outread must be greather than in Infeed when pumping. System controling continuously every second last 9 seconds changes after 10 sec from the start.
Last edited:
Kim Gold
Member
If you capture the tank level when the pump is started, and check the level after 10 seconds to see if it has changed. If it has not changed, generate an alarm.
Here is some sample logic.
Kim
Here is some sample logic.
Kim
Allen Nelson
Member
This code fragment may get you started.
'
There are all sorts of improvements to make to this, such using LEVEL minus DEADBAND instead of LEVEL, and changing the EQU to an LEQ, and adding a GRT to the MOV branch
Also, since you are also likely to stop your pump when you get the alarm, you may need to latch the alarm (lest the dropping of the alarm bit cause the pump to immediately restart). Of course, you'll then need to know when to unlatch the alarm.
PUMP +--- EQU --+ +---- TON --+
---| |----+--| LEVEL |----+----| ALARM_TMR |
| | STORAGE | | | 10 SEC |
| +----------+ | +-----------+
| |
| | ALARM_TMR ALARM
| +-----| |------( )
|
| +---- MOV --+
+------------------------| LEVEL |
| STORAGE |
+-----------+
'
There are all sorts of improvements to make to this, such using LEVEL minus DEADBAND instead of LEVEL, and changing the EQU to an LEQ, and adding a GRT to the MOV branch
Also, since you are also likely to stop your pump when you get the alarm, you may need to latch the alarm (lest the dropping of the alarm bit cause the pump to immediately restart). Of course, you'll then need to know when to unlatch the alarm.
Mabye
I hope this helps. Its been awhile since I messed with AB's( I am doing fanuc's now). But I often felt that my employer pays me too write programs so that Every one understands. Also the whole key to this ladder is the actual turbulance vs the speed of your senor reactense,in other words the timers times may need modifying.
I hope this helps. Its been awhile since I messed with AB's( I am doing fanuc's now). But I often felt that my employer pays me too write programs so that Every one understands. Also the whole key to this ladder is the actual turbulance vs the speed of your senor reactense,in other words the timers times may need modifying.
JustDaveIII
Member
Here's my take:
Kim Gold
Member
JustDaveIII, what will happen after 10 seconds when you move the TNK_LVL to LAST_LVL?
Won't that cause the alarm to pickup on rung 1 as CHECK_TIME.DN bit will be done.
If you add a N.C. (Examine if Open) CHECK_TIME.DN bit to rung 0, the logic will work. But you will need to redo the rung with the SUB instruction on it, as it is a Output instruction and cannot go in that location in the rung.
Won't that cause the alarm to pickup on rung 1 as CHECK_TIME.DN bit will be done.
If you add a N.C. (Examine if Open) CHECK_TIME.DN bit to rung 0, the logic will work. But you will need to redo the rung with the SUB instruction on it, as it is a Output instruction and cannot go in that location in the rung.
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JustDaveIII
Member
Kim - you're absolutly right. Forgot to reset the timer. And not putting in actual valid addresses didn't let me verify it.
Dave
Dave
Alan Case
Lifetime Supporting Member
Hi, I cant figure out how to paste an image but here is a real quick bit of code. Obviously it needs filling out but it will give the idea. I have attached an image of the code so I hope that is viewable. Maybe someone else could post the RSLogix image of it for me.
BST XIC S:4/9 OSR B3:0/0 MOV I:1.0 N7:0 NXB XIO S:4/9 OSR B3:0/1 MOV I:1.0 N7:1 NXB EQU N7:0 N7:1 OTL B3:0/2 BND
Alan Case
BST XIC S:4/9 OSR B3:0/0 MOV I:1.0 N7:0 NXB XIO S:4/9 OSR B3:0/1 MOV I:1.0 N7:1 NXB EQU N7:0 N7:1 OTL B3:0/2 BND
Alan Case
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