Created Date: August 20,2008

Created by: KPrice

wrumbaugh, I can suggest a very simple test that we have used. Basically, while the VFD is commanded to run, store the actual encoder count in a (double) V-memory location, then after a suitable time delay, store the actual encoder count in a second (double) V-memory location. Compare (double) the (2) V-memory locations. If the (2) values equal, then set an alarm bit. Do this continually while the VFD is commanded to run. You can display the alarm bit state on the C-more. Also put an alarm reset button on the C-more. The time delay is set to allow time for the encoder to count between the (2) count samples. Hope this helps.

Created Date: August 22,2008

Created by: KPrice

I tried replying to your message, but apparently my reply had too many character, it would not accept it.

To "take a snap shot ", use a PD relay output. I'll try to draw what I am trying to say. Does this make sense?

MTR

RUN

Y0 T1 C1

--] / [------------RST C10

Created Date: August 22,2008

Created by: KPrice

The drawing didn't turn out so well. It looked better when I drew it. I'll try this export. Hope this is better.

PLC 260

// Rung 1

// Address 0

#BEGIN COMMENT

"Motor Run output enables encoder test timer, timer self-resets. "

#END

STR Y0

ANDN T1

TMR T1 K20

PD C1

// Rung 2

// Address 6

#BEGIN COMMENT

"Encoder Test PD relay contact takes a snap shot of the encoder counts when timer "

"resets. "

#END

STR C1

LDD V2000

OUTD V2002

// Rung 3

// Address 9

#BEGIN COMMENT

"Current encoder counts are compared to encoder count snap shot timer time interval. "

#END

STR T1

LDD V2000

CMPD V2002

// Rung 4

// Address 12

#BEGIN COMMENT

"Encoder alarm relay is set if encoder counts do not change within timer time interval. "

#END

STR T1

AND SP61

SET C10

// Rung 5

// Address 15

#BEGIN COMMENT

"Encoder alarm reset bit resets encoder alarm. "

#END

STR C100

RST C10

// Rung 6

// Address 17

NOP

#BEGIN ELEMENT_DOC

"Y0 ", "Motor Run ", " ", " "

"C1 ", "Enc Test PD ", " ", " "

"C10 ", "Enc Alarm ", " ", " "

"C100 ", "Enc Alarm Reset ", " ", " "

"T1 ", "Enc Test TMR ", " ", " "

"V2000 ", "Enc Count 1/2 ", " ", " "

"V2001 ", "Enc Count 2/2 ", " ", " "

"V2002 ", "Cnt Sample 1/2 ", " ", " "

"V2003 ", "Cnt Sample 2/2 ", " ", " "

"SP61 ", "Acc=Inst ", " ", " "

Created Date: August 22,2008

Created by: Bob S BN

To the Forum Moderator

I see KPrice had the same problem I had yesterday trying to draw a quick few lines of code, and the spaces get deleted when you post and is suddenly unreadable.

I was trying to help a newcomer to PLC's and thought the picture of the ladder and his trying to then enter it on his own would have taken him a long way in understanding the use of the software.

Is there anything that can be done to easily fix this code typing issue??

Thanks, Bob

Created Date: August 22,2008

Created by: Do-more PE

The only way to do it is to use the UBB tag and also used a fixed font such as Courier New. It still takes a bit of playing with, but it is close.

An easier way is to just type it up in Directsoft, do a screen cap, save it with Paint as a .jpg and upload it. You can put it inline with the UBB tag.

But then the easiest way is just to upload the Directsoft project as a .zip archive.

MTR

RUN

Y0 T1 C1

--] /

http://forum.automationdirect.com/attachment.php?attachmentid=17&stc=1&d=1219437723

Created Date: August 20,2008

Created by: wrumbaugh

Have an application that uses a DL06 PLC with a HO-CTRIO installed and running a quad encoder. Looking for some suggestion on how I might program some logic that would monitor potential problems with encoder (IE broken belt, coupling slippage etc) while application is running. In this case we have a GS2 VFD that is running multispeeds and encoder provides us positioning information. We are also using a Micro CMore with this so in addition to stopping the operation I believe I could set up alarms to post warning text of encoder problems. However need some programming ideas on how to actually verify encoder problem exist. Thanks