Data collections from PLC`s

General
1

I have a SCADA system with 3-4 PLC`s and looking into building a data collector with Node-RED and push the data forward to AWS.

Is there any limitations on number of tags ? Is it only come down to the hardware?
Example 500tags x 3 PLC`s example, is that a issue?

Can I run these on a Raspberry PI?

2

Ethernet comms?
Serial Comms?

PLC make and model?
PLC protocol you are using?

Node-red-contrib nodes you are using?

how often will you read values?

What have you tried?

Do you read "tags" individually? or as a batch? (hint batch read is MUCH better)

Are you replacing the SCADA system with Node-red?

Does your SCADA currently connect to these PLCs?

Does your SCADA support writing to data AWS?

Will you be reading data from SCADA or PLCs?

3

We are researching different technology for data collection from PLC`s and pushing it forward to AWS.
My questions was meant to understand the performance and limitation in Node-RED.

Sampling will typical be per second.

Is Node-RED meant to be 10-50 tags total or can it handle 1000-2000 tags...

Looking forward to hear from you.

Ethernet comms? yes
Serial Comms?

PLC make and model? Can various but a example is AB CompactLogix Series
PLC protocol you are using? EtherNet/IP

Node-red-contrib nodes you are using? don`t know?

Are you replacing the SCADA system with Node-red?

Does your SCADA currently connect to these PLCs?

Does your SCADA support writing to data AWS?

Will you be reading data from SCADA or PLCs?

4

I currenty use Node-Red to gather Weather information from 7 different GPS locations (And 7 different Tags for each) every 3 minutes so that is 23,520 tags read every 24 hrs. and then publish back to my Scada system using Mqtt Sparkplug B protocol.

And on top of that I gather Stock Market Data 5 tags every 3 minute which equals 2400 tags every 24 hrs and this data also get publish back to my Scada Server using Mqtt Sparkplug B protocol.

I run this from a Raspberry Pi 4b that just runs on my VPN.

I have also wrote a program using Pycomm3 that will read tags from several on my Plc's and publish all of then back to my Scada Server using Mqtt Sparkplug B protocol. I have done this for 1000's of tags on a daily basis and had no problems. (However, I'm not currenty using this at the moment)

Just information that might help in your disicion making process.

1 Like
5

Here is another related thread that might help with your evaluation: Can we log 2000 tag data into MySQL - #6 by Steve-Mcl

6

From my experience node-red is not a bottle neck, main reason is PLC driver optimization.

As mentioned:

But also tag size is important: 16 tags of BOOL type will be equal in size of 1INT. So you should calculate size in bytes of your tag list.

Then comes sampling - 4000bytes of tags from Siemens PLC were read every ~3.5s. While 200bytes took ~200ms. I didn't investigate if dependency is linear.

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