Allen Bradley 1747-L30C Online Monitoring...

Andy S

Member
Join Date
May 2006
Location
England
Posts
40
Hello All,

Although I'm a newbie to posting on this forum I have used it many times in the past for help and advice - thanks to all you guys!

Anyway, my problem is that I have a customer that wishes me to connect to an Allen Bradley 1747-L30C PLC to help diagnose a problem that they are having with their production line.

Although I have used the SLC 500 (5/01 - 5/04) range in the past I have never connected to this type of processor.

Therefore I was wondering if RS Logix 500 and either the 1784-PCM4/B or PCM5/B lead would do the trick?


The customer has also mentioned that the code is backed up to an Eprom.
This is something that I have never done before but I assume that the latest version of the code could be written to the Eprom from RS Logix when connected to the PLC?



Thanks in advance for your help, Andrew
 
Hi Andy S.

The 1784-PCM4/B and PCM5/B are used in combination with a 1784-PCMK card.
The PCMK card is a bit expensive. It is a card for the PCMCIA slot in the laptop.
You might consider a 1747-UIC. It is a DH485 adapter that connects to the laptop via a USB port. It is much less expensive than a PCMK.

edit:
I notice that you have connected to a SLC5/01 before. The communication to the fixed hardware style is the same (DH485). You probably have the necessary hardware allready.

When you download the program to the PLC it is stored in RAM only.
The program is only stored on the EPROM if someone activates the "store to EEPROM" function in RSLogix.
 
Hi JasperMP, and thanks for your reply.

I failed to mention that I already have the 1784-PCMK card and leads, but anyway I have done a bit of digging on the net and confirmed like you have that it’s a DH-485 connector on this PLC type, so the PCMK card and 1784-PCM4/B lead (with RJ45 jack) should allow me to get online.

Thanks again for your help,

Andrew
 
The program is run in RAM in the PLC. The program can also be stored in the EEPROM, if that chip has been installed in the PLC. The PLC may load the program stored on EEPROM when booting up, if that was set in the program. I beleive it has to be set in the program currently running in ram AND the one stored on the EEPROM.

If making updates to the program, make sure the new one running in RAM has also been burned to the EEPROM. If you don't the modifications may be lost as soon as the PLC is rebooted.

Programs stored in RAM and/or EEPROM, when you upload from this PLC or EEPROM, you will not have any doumentation to work with. Hope they also have it on disk.
 
Last edited:
Good morning to you dalem and thanks for your post,

They do have a disk, so fingers crossed it will have the original code with documentation attached. Thanks also for your info on the EEPROM. I assume like JesperMP pointed out that the programme could be burned to this from RS Logix?

Cheers

Andrew
 
Andy S said:
I assume like JesperMP pointed out that the programme could be burned to this from RS Logix?

In RSLogix500, it's under the "comms" tab. You need to be online with the PLC to burn to EEPROM. I beleive it take the PLC out of RUN mode, so be ready for that.

Not sure why, but now that I'm using Win XP, I sometimes have probelms burning the EEPROM. I beleive the error message is something about not being able to get ownership of the processor. Usually, when this is happening, I am plugged into the Panelview 550, which is hooked to the SLC500 L20A unit. Don't remember that issue with my Win 95 laptop. To get around this, I hook up directly to the SLC itself. If still problems, I reboot the PLC then do the D/L or EEPROM burn just after it starts up. This issue might have also come about, when I upgrades my PB32 software.
 
Last edited:
As Dalem States its under the comms tab

Comms > EEProm > Store to EEprom or Load From EEProm

If they have the ladder on disk, you may want to check thats its the same code thats in the processor!

Your dh485 pcmk will work just fine
 
Don't Forget About the Status Bits !

Don't forget to use various status bits for the following, if required:

Memory module load on boot is bit: S:5/8
Password mismatch is bit: S:5/9
Load memory module on memory error is bit: S:1/10
Load memory module always is bit: S:1/11
Load memory module and RUN is bit: S:1/12

Check out HELP in RS Logix for more information.

Also, I always had the problem when using a EEPROM on the SLC with a PanelView that changes made through the PanelView were lost if the EEPROM wrote over it on any of the above conditions, if set up that way.
 

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