Embedded Datalogging on PLC

I need to log data onto a PLC that is not normally connected to a network or HMI terminal. I need periodic (every 15 minutes) storage of 3 analog values and one digital value. I only need the last 24 hours of data so I'm planning to build a queue that will overwrite the oldest data so I don't run out of space. I have written programs to store the data directly into the PLC memory in the past but I don't want to hard code every register. I know Siemens has a way to use pointers to programatically change registers but I have never used them. I don't know what Rockwell offers. Does anyone have suggestions or example code? I can use either a Siemens S7-300 or a ControlLogix. Which will be easier for this type of program? (I have done some basic programming on both)

Thanks for the tips

If you'd consider something besides those two, then the Unitronics Vision 280 series will do it with ease. $600 for the PLC (with touchscreen!), probably $300 for a snap-IO module with the IO you mention. The V200-18-E5B looks like what you need.

One under-credited feature of the Unitronics line is it's built-in database. This is a separate memory area, fully configurable, on-board flash-ram storage. There are function blocks to read and write values, row and column manipulation, copy and clear functions - you name it.

It's very easy to program if you have a little experience you can pick it up quick. As an added bonus, the programming software is a free download. As an even greater bonus, it has an OPC server, and some specialized apps to collect and store data from the internal tables onto a remote computer - also free.

Did I mention modbus compatability?

www.unitronics.com

TM

Ah, I didn't read closely enough. I see you already have a PLC on the machine and are trying to log data off of it, and no network availablity. Hmm, you got a problem there.

Unfortunately, the only advice I can offer is, I use rewriting que as well, so it's a fine way to go. But as for the rest, good luck!

TM

In CLX you could do this with timed task that runs every 15 minutes, and then use structured text to record the data and increase your index number.

I did not fully understand the details of the process so not sure if what I am about to mention is applicable.

There are numerous types of data loggers available some can be connected to a communications port of a PLC and some can take the actual signals and record them. In most cases they can retain values for at least a month or so depending on the frequency they are updated. Also most can be directly connect to a PC and place the data into an Excel spreadsheet.

This is an example of a datalogger that can connect to a PLC;
http://www.entertron.com/logger.htm

This site has numerous types that can be connected to the devices i.e. analog etc. http://www.davis.com/showl5.asp?L5ID=3

While I am a huge fan of the control logix platform, I'm just chiming in to inform you that the MicroLogix 1500 PLC has a respectably sized datalogging function file built in. It might be something to consider.

i did this a couple of months ago on a press with the cycle time. when i get to work tonight i will get the logic and post it for you. i don't have it here right now.

Yea, I got beat to this reply, but, the 1500 does have a nice capability for this. You have to do some digging, but, its all there.

her is that logic it's in AB format maybe one of the nice peeps here will put it in pdf format for you if not i will get it later

For logging like this I've used a software called XLReporter(www.sytech.com), what this does is basically collect data from the plc tru the rslinx (OPC server)and save it in an Excel sheet. You can configure it to collect for shifts, events, periodically etc, you can also configure it to generate a new sheet every day, shift, month, year etc.

widelto

pdelno said:

her is that logic it's in AB format maybe one of the nice peeps here will put it in pdf format for you if not i will get it later

Click to expand...

Nice person putting it into pdf

Its for an AB SLC range btw.

thanks 504Bloke logic at work pdf stuff at home thanks

Poor Mans Data Logger

If you just need it to log ~ every 15 mins, one of these should should work. If u need it more accurate, i guess you could run a periodic task and keep the clock synchronized with the Control Logix Clock Tool


RS Logix 5000 V 13

Twalter,

Ron provided the below link in a previous post.

You will want to review the information, but this might do what you are wanting to do.

http://www.entertron.com/logger.htm

To date, we know it works with our ePLCs, Idec and AB Micrologix. I can not guarantee that it will work with Siemans or Controllogix.

So long as you have an ASCII output, it should work.

Single piece price is $195.

Please note that we are the manufacturer of this product.

Hope this helps.

God Bless,