I know there have been several of us contemplating whether or not to use the Micrologix 1100. I have finally got an application to use one on and I thought I would share my first impressions with you.

First here is a little background on the machine. I built the controls for the machine about 4 years ago using a Micrologix 1200. It has 4 expansion I/O modules, two 1762-IW16s, one 1762-OW16, and one 1762-IF2OF2. It uses one high speed counter (Input 0 and 1) hooked to an encoder and uses the 1762-IF2OF2 to control a AB 2098-DSD-020 servo drive. It uses a Panelview 600 DF1, 2711-T6C16, as a HMI.

I was asked to make some upgrades to it that was going to push the data memory over the Micrologix 1200s 2k limit. It was also to be hooked to the Ethernet network for data acquisition. I probably could have used a memory module and some 1761-NET-ENIs to do it but it seemed like a perfect time to try the Micrologix 1100. This was a much cheaper solution but the machine could only be down twice for a half a day each time. All other program changes would have to be made in 2 minute openings when new parts were being loaded. So not only did this test the capabilities of the Micrologix 1100 but also how easily it could be swapped for a Micrologix 1200.

I/O - There are some things you need to watch out for when planning to upgrade to a Micrologix 1100 or designing a new project for that matter

1. There is only 10 inputs and 6 outputs on the Micrologix 1100 compared to the Micrologix 1200s 24 inputs and 16 outputs. I got lucky on this one. Most of the Outputs went through the expansion modules and I had enough spare inputs on the IQ16s to move all of the inputs to the expansion module. In the end I only had the encoder on inputs 1 and 2 and used five of the base outputs.

2. BIG WARNING    The Micrologix 1100 only supports 4 expansion modules compared with the Micrologix 1200s 6 expansion modules. I had some other questions for Rockwell and tech support did inform me of this when I was talking to them. Lucky for me, I had exactly 4 expansion modules.

3. The analog inputs are only 0 to 10 VDC and you can't configure the data format like you can with the 1762-IF2OF2.

Program Conversion

At this point I converted the Micrologix 1200 program to a Micrologix 1100. It went very smooth but it erased my expansion module including their configuration and set my input filters on inputs 0 and 1 back to their defaults so the HSC function file would not count. After making some changes I needed to put the program back into to do some testing with the existing Micrologix 1200 and ran into some problems during the changes and testing.

1. Message configuration. I already had some messages that were used on Micrologix 1200s through 1761-NET-ENIs to do the exact same communications so I started with them as a base.

a. I changed the message to go through channel 1 and I found I could not figure out how to the message path.

b. So I went to the instruction set help and selected message and there was no documentation apparently added for the 1100. Then went to the find tab of the help dialog and put 1100 in and there were the instructions for configuring the 1100 Ethernet message. I guess Rockwell forgot to put a link to it in the message help area.

c. There is a new data type, ROUTING, for configuring your path.

2. Converting a 1100 program back to a 1200 program. I needed to test some of the new code and converted the 1100 program back to a 1200 program and ran into a flaw in RsLogix 500.

a. It erased my expansion modules and set my input filters back to default.

b. After the conversion I could not get the program to verify. In routine 20, rung 20 for instructions 1 and 2 it said "ERROR, Instruction not allowed on last rung." The rung only had a simple NEQ statement and a MOV statement that was all that was in it.

c. Also there were 22 rungs in the routine which means that rung 20 wasn't event the last rung.

d. After about an hour of looking at it, I realized that my Ethernet message instruction was on rung.

e. I viewed the configuration of the message and it had reverted to an acceptable message instruction. But when I tried to cut the rung out of it RsLogix 5000 came up with a memory error and crapped out. After several tries and I don't remember the final method I got the message instruction out of it and the program verified fine. I created a message instruction with the exact same parameters and it still verified fine.

f. So when you are doing your conversion and need to test on the old controller do not convert your program back to a 1200 program. Use two programs and copy/paste your rungs back and forth.

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