Dl06

I have a DL06 with analog I/O cards and C-More touch panel controlling a servo motor. In my 'manual' mode the setpoint input works as it should and all scaling is OK. When switching to 'auto' mode I want the PLc to increase the speed of the motor by a given amount every 5 seconds. The program does the first increment and then seems to get stuck on the next scan. I have a counter that tracks the number of scans that I monitor in the 'Data View' feature and it increments every 5 seconds but still no increase in the servo speed. Also, if I increase the magnitude of the increment it will speed up on the first scan but gets 'stuck' on the second. Please help.

PS. I am new to PLC programming.

can you post your file?

Here ya go. Thanks for having a look.

// Rung 1 Address 0 ANLGIN K0 K1 K8 K0 V400
// Rung 2 Address 38 ANLGOUT K0 K2 K8 K1 V420
// Rung 3 Address 74 STR SP1
BCDTORD V400 K0 V2000
BCDTORD V402 K0 V2002
BCDTORD V404 K0 V2004
BCDTORD V406 K0 V2006
BCDTORD V410 K0 V2010
BCDTORD V412 K0 V2012
BCDTORD V414 K0 V2014
// Rung 4 Address 642 STRN C1
LD V450
OUT V424
// Rung 5 Address 645 STR C1
ANDN T1
TMR T1 K50
// Rung 6 Address 650 STR C1
ANDPD T1
LDD V402
ADDD K5000
BIN
OUTD V424
INC V2400
End

When T1 expires, you add 5000 to V402. The problem is that V402 never changes, so the next time T1 expires, it adds 5000 to the SAME value as last time.

Assuming you want V402 to always be the starting value, use a different register to store the increasing value. I chose V3000-V3001 as this 'different register', but you can use whatever you want.

(Paste this code into a .txt file and then chose 'File-->Import-->Program' in DirectSOFT)
I added an additional rung (rung 6) to move V402 to V3000. This resets V3000 to your starting value every time you switch to auto.

On rung 7 (your original rung 6), I used V3000 in place of V402, and added an additional OUTD instruction to overwrite V3000 with the sum of the addition. Now each time that rung executes, it will have the NEW value in V3000.

Let me know if this works...



-Eric

Thanks. I had another person give me the same advice. Any reason that V402 does this behavior since it is the real time input from the analog card? It does register an increase the first scan then craps out. Just trying to understand the way the machine 'thinks'? Thanks again.

ColinCarew said:

Thanks. I had another person give me the same advice. Any reason that V402 does this behavior since it is the real time input from the analog card? It does register an increase the first scan then craps out. Just trying to understand the way the machine 'thinks'? Thanks again.

Click to expand...

What is the analog in connected to? For that matter, what is the analog out connected to? You said servo motor, but what is this motor connected to? Remember, I can only 'see' what you tell me...

Run your original program and watch the value of V402 while running in 'auto'. Does it increase? Based on your 'crapping out' result, I'm guessing that it's not. With your original program, the 'output' value will only be 5000 greater than the input each time T1 expires. If the input doesn't change, neither will the output.



-Eric

Tried your solution and it worked great. Thanks. As for your other questions, the analog cards are reading and feeding back through the original control boards for the servo motor. We have done a retro fit on an old control panel. After reading your fix I realized that your sequece of events go read,store,calculate where I was just reading and calculating. Since the analog card reads continuously and the program needs time to work maybe it is the timing of the system that I did not take into account?