Understanding LL frequent forms

[cwal61]

One Shot used to create 2 second pulse. Then shift word and add 3 values.

 

[Steve Bailey]

The rungs I posted earlier were rungs 80 and 81 of the program block, "MANUAL" and are immediately before the rung that Cal posted.

If you modify rung 80

AUTO_EN  M0343  RY3APR1 M0432  M0448             M0342

--] [-----]/[----]/[-----]/[----]/[---------------( )-

to eliminate the 343M contact as below

AUTO_EN  RY3APR1 M0432  M0448             M0342

--] [-----]/[-----]/[----]/[---------------(^)-

you can eliminate rung 81

I checked to make sure that M343 isn't used anywhere else in the program. If you modify any other roll-your-own one shots in the program be sure to check for any other usage of the address assigned to the coil instruction before you delete the second rung.

 

[CalG]

Steve

That looks good!

I'm pretty careful to search the entire logic for instances of any instruction or reference I am interested in.

I feel some level of impunity in that the original program is safe inside the EEPROM that is securing the CPU memory. IF I stay away from THAT SCREEN, I should always be good.

Plus, I have the memory dump (download from the plc) saved twice ...maybe I should do it again ;-)

Looking at the paper copy now....... Then I might do an "edit".

Does LM90 have the equivalent to a "REM" entry that ignores any entries on the line beyond. (like a batch file)

I know it does for text.

Thanks!

 

[Steve Bailey]

I feel some level of impunity in that the original program is safe inside the EEPROM that is securing the CPU memory. IF I stay away from THAT SCREEN, I should always be good.

Be careful in your assumptions!

According to the program file you sent me that system is set up to get its program and register data from RAM, not from EPROM.

There are two chip sockets on a CPU311 baseplate. One is labeled "System PROM" and contains the PLC firmware. The other is labeled "Program PROM". Is there a chip in the second socket?

 

[Bit_Bucket_07]

Does LM90 have the equivalent to a "REM" entry that ignores any entries on the line beyond. (like a batch file)

"Not" the "Always On" status bit is equivalent to the AB "AFI" instruction. I'm attempting to recall from memory, but I think it's %S07.

As for blocking an entire rung from execution without editing the rung, that would be much more complicated.

 

[CalG]

Yes there is

Be careful in your assumptions!

According to the program file you sent me that system is set up to get its program and register data from RAM, not from EPROM.

There are two chip sockets on a CPU311 baseplate. One is labeled "System PROM" and contains the PLC firmware. The other is labeled "Program PROM". Is there a chip in the second socket?

Yes there is

 

[CalG]

I just thought of something that could have really hurt

Be careful in your assumptions!

According to the program file you sent me that system is set up to get its program and register data from RAM, not from EPROM.

There are two chip sockets on a CPU311 baseplate. One is labeled "System PROM" and contains the PLC firmware. The other is labeled "Program PROM". Is there a chip in the second socket?

The EEPROM may very well NOT Contain the contemporary logic data.

Now that would be disappointing ;-)

I'll wait till I'm a bit more comfortable with LM90, before pulling the data from there however. Error on the side of caution.

 

[Steve Bailey]

Go to the Logicmaster "Utilty" menu <SHIFT + F9>, then F10 (prom). You can copy from EEPROM to RAM or from RAM to EEPROM. The "Verify" choice will compare RAM with EEPROM and report differences.

If you want to try to read what's in the EEPROM, remember that it will copy the EEPROM into the PLC's RAM and overwrite what's already there, so be sure you back up the RAM using Logicmaster before examining the EEPROM.

Details about the functionality of the menu selections can be found in chapter 8 of the manual GFK-0466.

 

[CalG]

Steve, I was just rereading that document at this moment!

Seems like the varify option is a safe first start.

If I do it right ;-) All thumbs at the keyboard......

Did the varify operation. The Register data did not varify. No comments on the logic or config.

I wonder if that is because I added nicknames and descriptions to the references and uploaded the .csv file.

 

[Steve Bailey]

No surprise there. The miscompare of the %R memory means that the stored data values in the %R memory locations aren't the same in RAM and EEPROM.

For example, %R0001 could currently contain a value of 10 in RAM and have a value of 20 stored in EEPROM.

Do another verify without comparing data values. If the ladder logic and configuration are the same you should get the message "Verify complete. No miscompares detected."

 

[CalG]

no miscompares there!