Retentive recipe data on SLC

[kolyur]

I am using an SLC 5/03 for recipe handling. The recipes are stored in one data file (16 recipes of 16 words apiece) and are accessed with indirect addressing. Using an attached PanelView, the operator can call up the different recipes and edit them.

This has worked great with one exception... the operator's modifications are easily overwritten if somebody (usually me) downloads a program update without uploading data table information first. I have read in other threads that it is not possible on the SLC platform to download only the program files without the data files.

So I was looking for a way to keep the recipe information safe and I had the idea of adding a small PLC to the network (DH485) which would not be running a program but I could read and write recipe info to it using the MSG command. I can get a ML1000 for under $100 but I found out that the integer file is only 105 words and you can't add more data files. So the next step up is a ML1200 ($300), which is not unreasonable, but it seems like overkill just for data storage.

Has anyone tried this or any other methods for retentive SLC data storage? I would be interested to hear other opinions.

Thanks,
John

 

[nnixon6]

The SLC data tables have a check box under properties that allow you to protect them from overwrite.

 

[OkiePC]

I've got the same situation. I do all mods with online editing. I open two instances of RSLogix500. I copy and paste from the updated version to the running processor when changes are required. I don't have to stop the machine or disrupt the recipes this way. It takes a little longer if you have a bunch of changes. I also have an Excel workbook that can gather all recipes from all my machines from my office using DDE. I use it for backups monthly. It won't necessarily be current though, if a processor dies, for example. I like your idea with the Micrologix. There should be a device on the market for your specific purpose without any I/O. I don't have any experience with Eprom modules, but I don't think they give you the flexibility to decide what to store on them. Some one needs to market a ramdisk card with removable media that fits 1746, 1756, and 1771 I/O chassis!

 

[OkiePC]

nnixon6: What happens to the data tables if you have static protection and attempt to download the SLC program? I don't have a spare to test with.

Also, if your HMI is connected through a comm channel and writes directly to the recipes, static protection will disable it from making any changes.

 

[kolyur]

Unfortunately the data file protection options do not protect the data from program transfers. They only prevent changes from a communication device other than RSLogix, such as an HMI.

Okie: Thanks for your input. I try to use online editing as much as possible but with larger modifications I like to work on it in my office. And I can't be sure that other people who have access to the program will use online editing rather than doing a straight download.

I did find a PCMCIA storage module that fits right into the SLC backplane and can supposedly store up to 2GB of data. This would be perfect for my application but costs $1500.
http://www.mangiapane.com/modules.htm

 

[OkiePC]

Hey, that device is very cool ... Too bad it costs so much. I just bought a 512mb usb sandisk for $59 ...
Maybe someday the price gap between industrial and commercial products will shrink .

Unfortunately the data file protection options do not protect the data from program transfers. They only prevent changes from a communication device other than RSLogix, such as an HMI.

Thanks for the research ... it's what I figured would happen.

 

[panic mode]

sounds like small MCU project with CF interface and (partial) DF1 support would be perfect. worse case this could be PC.