SLC 150 SQO instruction

[kbradray]

I am converting an old SLC 150 program to be used with a newer SLC 5/05. I have done this with other 150s, but I have some instructions that I am unfamiliar with. Any assistance is appreciated. I am unsure that the SQO instruction is doing anything other than jumping into the ZCL zone. Please see the information below obtained from the hardcopy of the program.

SLC 150 Sequencer Table

I/O Address:18 17 16 15 14 13 12 11 902 -(SQO)-Grp 00
Hex Mask: 0 0
Binary Mask:0 0 0 0 0 0 0 0 Preset Value
Step # Hex Data Binary Data
00 00 - - - - - - - - 0001





SLC 150 Ladder



Conv. Prox. 203 --] [--------------(CTU)--- Conv. Counter 901 Preset= 6
Counter DN 901 --] [--------------(SQO)--- Seq. Out 902 Grp 00
????? 902 --] [--------------(ZCL)--- I think I can use a SUB here
????? 844 --] [--------------(LSR)--- I think these are Bits used later in prog.

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.

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-------------------(ZCL)—I think I can use a RET here

 

[kbradray]

Hosed up previous message.

This is a breif description of the hosed up previous message.

There is a counter which when done causes a SLC 150 SQO command to toggle. When this SQO command toggles it sets a ZCL output.

I was just wandering if someone can help describe the SLC 150 instructions SQO and ZCL or compair them to insturctions used today.


Sorry for the above and thanks for any assistance
Ken

 

[TConnolly]

Ken, can you post the PCIS program file?

As I read it the ZCL is something that is done for a single scan whenever the sequencer advances. The Sequencer is writing a bit pattern to outputs 11 through 18 and that bit pattern changes as the sequencer advances - its very similar to the SLC SQO instruction - but its hard to say exactly what the ZCL is for from that program segment.

You are correct in uning a conditional subroutine for the ZCL. Remember that in a ZCL zone any outputs are left in their last state until the ZCL is executed again so keep that in mind as you redesigning the program.

EDIT:
You can get the SLC100 manual and instruction set reference manaul from AB's online library at http://literature.rockwellautomation.com/idc/groups/literature/documents/um/1745-um001_-en-p.pdf

There is also a technote in AB's knowledgebase that describes how to deal with ZCL instructions when converting SLC100 programs to the SLC platforms.

 

[kbradray]

Thanks Alaric

I have already downloaded the 150 manual. The confusing thing to me is that in the sequencer table shows no mask and no binary data. I am only working from the hard copy, but I can see no use for this -(SQO)- output.

The knowledgebase article for the ZCL was very useful.

Thanks again.

 

[TConnolly]

Are output addresses 11 through 18 found elsewhere in your program? The SQO appears to be configured to write to those 8 addresses but if they are elsewhere in the program then its possible that the SQO was never properly programmed. Hard to say for sure without seeing it though.

 

[kbradray]

What I have discovered

For a better overview of what this program is controlling: It is a washer consisting of 3 washing stages and a conveying system. The program controls various heaters, blowers, and the exhaust fans along with the conveyor.



What I have discovered so far. The SQO instruction is just a dummy instruction which initiates the ZCL zone. An SQO can be used as a dummy and is discussed on page 11-1 in the SLC manual of the link you attached.



My ZCL zone consists of several –(LSR)- instructions. These are bit shift left instructions which I previously thought were controlling the conveyor system, but I can’t see where they are used in the program anywhere else. It is my assumption that this was installed in case it needed to be used later.



The rest of the program is pretty much self explanatory. I just wanted to get my hands around the first portion that I could not understand. I will try and put it here for you to take a look at in case I am missing something.


Conv. Prox. 203 --] [--------------(CTU)--- Conv. Counter 901 Preset= 6
Counter DN 901 --] [--------------(SQO)--- Seq. Out 902 Grp 00
SQO start zone 902 --] [--------------(ZCL)---
844 --] [--------------(LSR)--- 845
836 --] [--------------(LSR)--- 837
828 --] [--------------(LSR)--- 829
------ --] [--------------(ZCL)---


852 851 850 849 848 847 846 845
844 843 842 841 840 839 838 837
836 835 834 833 832 831 830 829
If I am correct the above table should be my registers for each LCR.

 

[TConnolly]

The SQO is being used as a single shot. When Counter 901 is done, SQO 902 is triggered. The next XIC 902 is true for only a single scan. The SLC100/150 doesn't have any one shot instructions so I'll wager that the original programmer used an SQO rather than build some one shot logic.

So you probably want to move all of the code in the ZCL zone to a subroutine and conditionally call the subroutine with a one shot when the counter is done.