Data Tracking on Index Conveyor

Hello All,

First time posting..

I need assistance on how to move data one step at a time through the PLC.

I’m working on a laser machine using a CompactLogix and an index conveyor.
I need to shift this [8 digit number] sent from VB.NET, one step each time the conveyor indexes.
When it gets to position 12, VB.NET will read the code and Laser the product with the I.D.

I have attached a file with some more detail.

Note: Each time the conveyor indexes a new 8 digit number is sent to PLC bit.

Thanks Very Much.

Welcome to the forum!

I'm assuming that you have the data transfer between VB.Net and the Compact Logix sorted? If so...

Use a FIFO (First In First Out) register.

It uses an array of any size (in your case, 12), and you load and unload data using the FFL and FFU instructions respectively.

So, each time you index, you will load the new value from VB into the "stack" using the FFL instruction. Once you have 12 values in your stack (.DN bit set), you will use the FFU to unload the oldest value, and send it to VB for etching.

For some good examples, drop an FFL and FFU instruction onto your rung, select them and click F1. The help file is quite comprehensive.

Thanks ASF for your reply.
I'm working on the FIFO now.
The FFL is updating each time the conveyor indexes but when it reaches 12 values I cannot seem to get the FFU to unload into VB for etching.

Please see the code I'm using.

Thanks.

You will need to 'command' the FFU only when the stack is full rather than 'hot rung' it.

Insert ahead of the FFU an XIC (Normally Open) instruction of the 'R08_d_FIFO_Tracking.DN' bit thus 'unloading' the 'oldest' of the stack values when all 12 rungs are filled.

You will also need to deal with what happens if the conveyor has to index without a new part being loaded, probably something like writing "00000000" into the fifo. There will be similar conditions to deal with during startup and shutdown.

Hi dmargineau,

Thanks for your reply,

I think you meant R08_d_Control_1.DN. If so it works now.

mendonsy: Good point, I will add maybe a MOV function if the conv indexes with no product and MOV all 0000000.

I will be testing code over next few days so if I encounter more issues I will add to this thread.

Thanks for your help.

irinjia said:

Hi dmargineau,

Thanks for your reply,

I think you meant R08_d_Control_1.DN.

Click to expand...

The FIFO control tag indeed it is 'R08_d_Control_1'...Toggling between 200% zoomed tabs without Copy/Paste......

Glad you sort it out...