MicroLogix 1100B - Bit writes

pmbreddy

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• Apr 23, 2013

• #1

I am trying to write or change values using ladder logic to B3 registers and I am not able to write any values to the same. I am not able to change values through RSLogix 500 as well. Any help with this is appreciated.

I am able to write values when I use MicroLogix 1100A series controllers.

 

dmargineau

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• Apr 23, 2013

• #2

What revision RSLogix 500 are you running?
For ML1100 Series B controllers you will need a minimum of 7.20.00.
Also, verify the B3 File State Protection and make sure is set to "None"; this feature prevents the respective file to be "communications written" but for when a Download is being performed.

 

Last edited: Apr 23, 2013

kolyur

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• Apr 23, 2013

• #3

A few additional possibilities:
- Make sure you don't have multiple instructions writing to the same B3 addresses. This will make it appear as if one is not working, and might also prevent you from manually modifying the data in RSLogix.
- If the write logic is in a subroutine, make sure it is being scanned. (A JSR should be executing somewhere.)

 

jkerekes

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• Apr 23, 2013

• #4

Also I think you can write-protect certain registers also. I don't have RSLogix 500 in front of me at the moment.

 

pmbreddy

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• Apr 23, 2013

• #5

I am using RSLogix 8.60 version with protection set to none.

 

TConnolly

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• Apr 23, 2013

• #6

Zip your program and attach it to a post.

 

pmbreddy

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• Apr 24, 2013

• #7

Attached is the program

ladder logic attached

 

pmbreddy

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• Apr 24, 2013

• #8

I am able to write values when I am in program mode and not able to do the same in Run mode. Does MicroLogix 1100B support online editing?

 

kolyur

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• Apr 24, 2013

• #9

You will not be able to change the value of B3:0/2 because it is used in an OTE coil. You should be able to manually change B3:0/0 and B3:0/1 in the data table, since they are not controlled anywhere in the program. Is this the behavior you are seeing?

Yes, the Micrologix 1100 supports online editing.

 

pmbreddy

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• Apr 24, 2013

• #10

I am not able to change values for B3:0/0 and B3:0/1 in data table.

 

kolyur

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• Apr 24, 2013

• #11

You aren't trying to force the bits, are you? You can't apply forces to internal bits. If you right-click on one of the contacts and select "Toggle Bit", the state should change (even in Run mode). I see there is no protection on the data file so I don't know what else could be preventing this unless you have an HMI or other device connected which is controlling those bits.

 

pmbreddy

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• Apr 24, 2013

• #12

I am not forcing any bit writes and also I am just connecting to controller via Ethernet to test it in the lab. No more configuration complications as I ma testing only controller in our lab.

 

TConnolly

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• Apr 24, 2013

• #13

If you are trying to change the value of a bit from the data table by just typing in a new value you need to press the ENTER key after you type the new value. You can't just click on the next value or tab off the value and expect it to change. This might not be the problem, but you wouldn't be the first person to get tripped up by that either.

Edit to add:
Try using the bit toggle. Right click the address above one of the XIC instructions and pick toggle bit.

 

Last edited: Apr 24, 2013

pmbreddy

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• Apr 25, 2013

• #14

My controller is in RUN mode when I am trying to change values and also I am using toggle option as you mentioned also tried to change value of a bit by pressing enter as well. Nothing worked out for me.

 

TConnolly

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• Apr 25, 2013

• #15

The program file that you posted showed that you were successfully able to change the value of bit B3/0 as that bit has a value of 1. Somehow you were able to do that.

Open the B3 file data window. Change the Radix to decimal. Click on the word and type in the number 6 and press the enter key. You should see the rung status change accordingly. Try it offline. Then try it online.