SLC 5/04 analog card configuration

[indubasu]

Can I change the analog module (8 channel analog) configuration i.e. write bits to the configuration file while online with the PLC? Do I have to turn off the PLC and download the configuration in order to do this?

 

[Mickey]

Simple answer yes. The new configuration will have to be written to the card.

What card do you have?

Also if you can post the file and tell us what card you want to change someone will be able to provide more help.

 

[indubasu]

1746-NI8 Class 1. BTW, not sure what the yes was for. do I have to stop the PLC to change configuration on just one of the channels or can it be done online without shutting off the PLC? The configuration of one channel does not seem correct (it shows disabled whereas it whould be enabled), rest are fine... so I was wondering if I could write the correct configuration for that channel online so that I could enable it i.e write a bit 1 in the appropriate place instead of the 0 that it is displaying currently?

 

[Mickey]

1746-NI8 Class 1. BTW, not sure what the yes was for. do I have to stop the PLC to change configuration on just one of the channels or can it be done online without shutting off the PLC? The configuration of one channel does not seem correct (it shows disabled whereas it whould be enabled), rest are fine... so I was wondering if I could write the correct configuration for that channel online so that I could enable it i.e write a bit 1 in the appropriate place instead of the 0 that it is displaying currently?

Again,

Yes.

 

[Ron Beaufort]

you really should post your program if it's allowed ...

yes, as my distinguished colleague Mickey says, you might be able to turn on the appropriate bit and thus enable the channel while you're online - and in the run mode ... that really shouldn't be a problem on most systems ...

but ...

in many programs you will have a rung (usually controlled by an XIC addressed to bit S:1/15) that uses a COP (Copy) command to "populate" the module's output words each time that the processor first starts up ...

here's the potential problem:

suppose that you do manually set the bits in the output file correctly - and the module starts working the way that it should ...

but ...

suppose that you do NOT set the bits in the "source" of the COP command (usually the source is in an integer file" ...

oops! ...

the next time that the processor goes into the run mode (after a power failure, etc.) then the "bad" data in the integer file would be written into the output file - and suddenly and unexpectedly you're right back in the same mess again ...

post your file if you're allowed to ... we'll be glad to take a look at it for you ...

 

[indubasu]

Hi Ron,
I attended your PLC 5 class in Sept 2008, not sure if you remember me.. yup I realized I have to put the correct config in both the N file and the O file for that channel. There is a problemn with the N file which copies to the O file, so when we lost power to the PLC this incorrect N file configuration got copied to the O file on first pass and thats where the problem is (for just that one channel and the two spare channels). I have to rectify the N config AND the output file status for that channel so that this does not happen again when we lose power. From the replies I get here, I assume I can do both the changes online.

Thanks,

 

[Ron Beaufort]

yes, certainly I remember you, Indrani ... you were one of my first "international students" - all the way from British Columbia ...

I'm 99% positive that you can make all of the changes that you've mentioned while "online" and in the run mode ... if you can post your program file (or email it directly to me) I'll be glad to confirm that for you tomorrow ... I have a 1746-NI8 module in the lab - I'll be happy to experiment and make sure that it all goes smoothly ...

good luck with your project ...

 

[Gil47]

If you can determine what the value is that needs to be entered into the N file, then enter it there, and then put a temporary branch around the S:1/15, with an XIC that you trigger to simulate the startup then remove the Temp branch

I did this and it worked a couple of months ago, on a running system that I could not shut down.

Adding it solely to the O file did not appear to work out in my case.

 

[indubasu]

I am sure we can update the O file only without updating the source N file coz thats what the folks before me have been doing .. and that is where the issue is. If they had taken the trouble of updating both the files, this problem would not have occured on power up. I am going to rectify this so that this does not happen again..

 

[Ron Beaufort]

there's a little bit more to the program that you sent me ... I'm working on it now ... I'll have an email for you soon ...

 

[Ron Beaufort]

Greetings indubasu ...

I installed a 1746-NI8 module in a spare chassis with an SLC-5/04 processor ...

I was able to change the configuration data in the Output words – and also the configuration data in the Integer words – both while "online" and in the Remote Run mode ...

as long as this is all that you do, I really don't think that you'll have any problem doing your configuration under these "online" and Remote Run conditions ...

I think that answers your main question ...

going further ...

be ESPECIALLY careful when working with the RSLogix500 software's Advanced Configuration feature for this module ... note that the documentation (wiring schematic, etc.) refers to the eight analog input channels as "Channel 0" through "Channel 7" ... BUT ... in the Advanced Configuration feature, the TABS ARE NUMBERED for channels 1 THROUGH 8 ... (I'm using RSLogix500 version 8.30.01) ...

specifically, this creates an "OFFSET of ONE" that turns into a trap for the unwary ... I've heard of cases where a programmer has tried to adjust the configuration for one channel – but has inadvertently been changing the configuration for ANOTHER channel instead ... naturally in some systems this could lead to a very bad situation ...

I'm going to post these particular answers on the forum since this might be of interest to other people – but as you requested, I certainly will not post any part of your program ... there is quite a bit more for you to consider in the email that I'm sending ...

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