Temperature logging with timestamp information

73project · Jan 20, 2017

I'm scoping a project that requires logging temperature readings from a RTD. The requirements are that the temperature is captured with a timestamp on 15 minute intervals, and also that the PLC will save a weeks worth of historical captures. This amounts to around 672 records to store to reach the weeks worth of data. With this in mind, I'm leaning towards a CompactLogix processor with a RTD card. I could then build a UDT for the captures, and then populate the with the temperature and time stamp on the 15 minute interval. I would shift the data at each new capture. Have any of you guys done something similar, or have any suggestions that may save me from making this more complex than it has to be?

bjh · Jan 20, 2017

It can be done cheaper, but your way of a CompactLogix with a UDT array that contains the temp reading plus the time stamp is clean, functional and what I would do also.

Saffa · Jan 20, 2017

I would take a look at the Unitronics Vision PLCs. They can log to internal memory and they have a simple tool for extracting the logged data.

That's if your application doesn't have a lot of other logic.

kallileo · Jan 21, 2017

In similar application I use a cheap temperature controller/transmitter with Modbus RTU capabilities and a HMI display to log the temperature. My HMI support up to 200000 samples to be logged into internal memory, SD card or USB disk. It can also display a history trend for quick check and it can export the data into .CSV file.
I think always better and cheaper to use a HMI to log data than a PLC if you don't need any logic.

padees · Jan 21, 2017

When I have to do data logging, I usually use a Red Lion Graphite terminal. Very easy to set up, and a lot of fun to play with. Plus, you can get an input module for your RTD. Those work pretty nice.

I had to log about a dozen points on a RC for a few weeks with an average of 18,000 lines per day. Worked really sweet! That was with a G306A.

gclshortt · Jan 21, 2017

http://accautomation.ca/click-plc-advancedhmi-communication/

The above sample link uses a Click PLC program to read the present value (PV) and the indicating lights on our Solo Process Temperature Controller. It will then write the set value (SV) to the Solo. This communication will be done using Modbus RTU protocol over a RS485 serial port on the Click. The AdvancedHMI package will communicate Modbus TCP over Ethernet to the Click PLC. We will be able to monitor our PV and set our SV on the Solo via the AdvancedHMI window.

Solo Process Temperature Controllers:
https://www.automationdirect.com/adc/Shopping/Catalog/Process_Control_-a-_Measurement/Temperature_-z-_Process_Controllers
Click PLC
https://www.automationdirect.com/adc/Shopping/Catalog/Programmable_Controllers/CLICK_Series_PLCs_(Stackable_Micro_Brick)
AdvancedHMI
https://sourceforge.net/projects/advancedhmi/

Regards,
Garry

grnick50 · Jan 22, 2017

If you are into Siemens you can check this out.

http://www.plctalk.net/qanda/showthread.php?t=107535

It is based on S7-1200 and it is packed with features.
It will definitely cost less than a Compactlogix solution and still be a high end solution.

ASF · Jan 22, 2017

Plenty of valid solutions here, but if you're set on using AB then I think you're on the right track with a Compact Logix and a UDT.

If you use an array of UDT's, you can just use a FIFO array to do all of your data handling, and it'll be very nice and clean.

73project · Jan 24, 2017

Wow! Thanks for all of your suggestions! It looks like there are quite a few ways to approach this project. I've never played with Siemens or Red Lion, and have not heard of some of the other listed hardware. Thanks for everyone's input.

automationtechie · Jan 31, 2017

http://www.icpdas-usa.com/dl_301.html

The DL-301 has a built in temperature sensor and logs data to internal memory. It can log temperature, humidity and pressure. It has a built in display and there is an Iphone App available.

shooter · Jan 31, 2017

If it is only a few, and a week, use a portable sensor with a battery and a USB connection. They are widely used for cooled cargo transport.

harryting · Jan 31, 2017

What you do would work just fine. However, it's worth thinking about how the data will be used. If the customer want the data in easily accessible form then you may want something that log into SQL DB or CSV file. Also, if there's existing HMI you may also want to see if you can use the HMI's logging ability.

73project · Feb 1, 2017

harryting said:
What you do would work just fine. However, it's worth thinking about how the data will be used. If the customer want the data in easily accessible form then you may want something that log into SQL DB or CSV file. Also, if there's existing HMI you may also want to see if you can use the HMI's logging ability.

The normal function of the system will be that the facility MES data collection system will be pulling a current value from a controller tag every 15 minutes. The collection of the weeks worth of data locally is only a failsafe in case the MES system is down. I haven't ever looked into using the HMI as the logging device. I will have to look into that further!

robertmee · Feb 1, 2017

Sounds like an environmental permit requirement...I've done lots of these and the same way you suggested. I store the samples, 15 minute averages and 3 hour averages...An intouch factory historian server pulls the data but if that link is down the data is still there.

Temperature logging with timestamp information

73project

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