micrologix 500 intructions

stu · Oct 10, 2008

good day to you, i am new to plcs i have been given a project at work to take out a automation direct plc and replace it with a micrologix 1200 there is a part of the auto programme which has a set and reset function but i dont know how to do it on the micro can anyone help? it might be me being thick
thanks
stu

Ken Moore · Oct 10, 2008

Latch (OTL) and Unlatch (OTU) are the AB version of set and reset.
Be warned, latches are retentive and will not be cleared on a power cycle.

alearon · Oct 10, 2008

Ken Moore said:
Latch (OTL) and Unlatch (OTU) are the AB version of set and reset.
Be warned, latches are retentive and will not be cleared on a power cycle.

Hello Sir,

I'm new at this, so i was thinking of asking ur advice on this.

u mentioned latched n unlatched will not be cleared on a power cycle. What does a power cycle means? does it mean that even if i switched off the plc and restart the latched output is still there?

Regards,
Al

jstolaruk · Oct 10, 2008

alearon said:
Hello Sir,

I'm new at this, so i was thinking of asking ur advice on this.

u mentioned latched n unlatched will not be cleared on a power cycle. What does a power cycle means? does it mean that even if i switched off the plc and restart the latched output is still there?

Regards,
Al

yes

alearon · Oct 10, 2008

jstolaruk said:
yes

thanks for your reply sir,

Another question, does this apply to AB only or all PLCs?

I'm currently learning mitsubishi PLC.

Thanks
Al

jstolaruk · Oct 10, 2008

Each PLC mfg or PLC model will be different. Check the programming manual for the model you are working with. (Sorry, I can't give you a direct answer about the Mitsubishi).

alearon · Oct 10, 2008

Thankyou sir,

It's ok . Fruits are sweeter when we pick them ourselves, right?

Regards,
Al

Ken Moore · Oct 10, 2008

Mitsubishi PLC's depend on the configuration. However, I believe the new PLC's have a set and reset instruction as well. It's been a long time since I worked with Mitsubishi PLC's, so my information may be incorrect.
See this thread on another board:
http://forums.mrplc.com/index.php?showtopic=10109

alearon · Oct 10, 2008

Thanks a bundle.

Cheers

alearon · Oct 10, 2008

Ken Moore said:
Mitsubishi PLC's depend on the configuration. However, I believe the new PLC's have a set and reset instruction as well. It's been a long time since I worked with Mitsubishi PLC's, so my information may be incorrect.
See this thread on another board:
http://forums.mrplc.com/index.php?showtopic=10109

Hello sir,
from the sample programs that i have, yes Mits do have set n reset functions. From the automation that i have, latched input will be refreshed when powered off.

Also i read through the thread u adviced and found out that they use M500 above as latched relays. do they mean that i can use m500 and above instead to replace the SET function?

I understand that you didnt work with Mits for a while but i'm in desperate need of a guru now..heh heh.

Thanks.
Al

stu · Nov 10, 2008

Ken Moore said:
Latch (OTL) and Unlatch (OTU) are the AB version of set and reset.
Be warned, latches are retentive and will not be cleared on a power cycle.

hi
so with rslogix 500 (micrologix 1200) how do you set and reset contacts safely?

Clay B. · Nov 10, 2008

stu said:
hi
so with rslogix 500 (micrologix 1200) how do you set and reset contacts safely?

The way I do it is to make use of the first scan bit. I used it to clear all of my latches and take the machine to a safe state when power is turned back on. S:1/15 is the adress. This bit is on for the very first scan of the PLC only. This applies to SLC's and Micrologix.

Generally I will only latch bits. I try to group these bits to gether as much as possible so on the fist scan I can do something like this

--[S:1/15]---------| CLR |
|B3:0 |

This way I do not have to create an unlatch for each bit I just clear the entire word.

micrologix 500 intructions

stu

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