Help with BSL RsLogix500

All:

I am having difficulty getting my rejected parts to eject at the correct station and I am requesting help in determining where exactly I have gone wrong with this program. It is my first time using BSL instructions and my newness is evident. having read this forum for a time I thought it prudent to enclose a zipped copy of the program for information.

Some system information:
SLC 500 Controller
There is no encoder on the conveyor.
I am using a prox switch between the stations to perform the bit shift.
I am using a Redlion G308 HMI

System Overview

Station 1 uses a cognex camera to detect if a gear is present
Station 2 used 2 cognex cameras to detect tire gap top and bottom of the part
Station 3 uses a cognex camera to detect if a bushing is installed
Station 4 uses a bimba feedback cylinder to insure that the screws are fully engaged
Station 5 is the reject station

There is a prox switch between:
Station 1 and 2
Station 2 and 3
Station 3 and 4

There isn't one between 4 and 5 and this may be the reason the whole system isn't working. I'm not familiar enough with the BSL instruction to effectively troubleshoot the program.

I figured this is the place to go for the help that I need.

Thanks in advance to those willing to help.

Chris

cmarinello said:

I am using a prox switch between the stations to perform the bit shift.
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There is a prox switch between:
Station 1 and 2
Station 2 and 3
Station 3 and 4

Click to expand...

Are you saying you're using more than one prox to drive the BSL? These things are normally driven with only one signal.

yes

cmarinello said:

There isn't one between 4 and 5 and this may be the reason the whole system isn't working.

Click to expand...

It would certainly help to have one. How is station 5 to know when there is an item present and thereby know whether or not to take action?

Also, as noted in my previous post only one signal is used to drive a (synchronous) shift register. By triggering the shift from random locations you are upsetting the overall timing. Additionally, even if you were to use only the first prox as the signal, unless the distance between each station is identical it's not going to work well.

IMHO, the way out of this is to:

• add a prox between 4 and 5
• discard the BSL
• replace the BSL with an asynchronous shift register, described below

When the item leaves station 1 move its status to register "A" (word or bit depending on the information needed to make a decision later). When the item leaves Station 2 the data in register "A" is modified accordingly and moves to register "B". And so on. When station 5 examines its incoming data from station 4, based on the newly added prox, it now knows how to act.

Doug,
Thanks for the suggestion. I will have another prox added between 4 and 5. Could you give me an example of an easy way to do what your saying? Which instruction(s) should I be using?
Thanks again for the reply...Especially on a Sunday
Chris

I haven't looked at your program yet but it is a good idea to use the BSL just to get near or inside the reject zone then use prox's downstream to determine the exact reject point.

Something like this for words:
Adjust the addresses for each station/register. The idea is to move a>b, b>c, and so on.

If using bits you'll need to latch or unlatch each bit depending on the result of the test.

De-bounce?

If you stick with the shift register only method, don't forget to make sure that the prox signal is de-bounced. The failure might be that you are getting an extra trigger, or when the conveyor stops, you could be at the edge of the prox hysteresis and the shift register empties due to vibration. Using a second prox to de-bounce the first is a great way since you aren't using an encoder.