Question on modbus please

Hi Friends,


I'm working on a SCADA Project with several sites having different PLC OEMs ( Siemens S7, Allen Bradley Control Logix, SLC, GE, etc).


The Plan is to Pull out data from them via Modbus TCP and Transfer to Mitsubishi MELSEC Q-Series PLC/M2M RTU(soft)then move on to Telemetry.



QUESTION PLEASE:
Is there a particular MODBUS that can actually pull out data from all- i.e. from Siemens, Allen Bradley, GE etc. OR Must I use Modbus from each OEM to pull out data from them and send to MELSEC Q-Series/M2M RTU for Telemetry?


I'll appreciate your response.
Regards

If all the OEM's have a Modbus TCP option that is good. If they do not, or options are too much of an investment, I have placed a small PLC like a AD Click with both Modbus TCP and Modbus RTU to communicate. I/O points are wired up in parallel with any of the existing PLC that I want to monitor.
Here is a link to the Click with Ethernet:
https://www.automationdirect.com/clickplcs/hardware/click-cpu#standard-e

I would look at AdvancedHMI to pull the data from each of the PLC's. You will find that you could use some of the existing drivers on the units to communicate without purchasing any additional hardware for communications.
https://sourceforge.net/projects/advancedhmi/
This is free software that will run in visual studio. It was written in VB.Net and is open sourced.

Basic installation and communication from AdvancedHMI to BRX Modbus TCP.
http://accautomation.ca/create-a-plc-with-hmi-training-and-learning-environment-free/
Video:
https://youtu.be/1rWI-A-nZdo

Hope this helps you out.
Regards,

gclshortt said:

If all the OEM's have a Modbus TCP option that is good. If they do not, or options are too much of an investment, I have placed a small PLC like a AD Click with both Modbus TCP and Modbus RTU to communicate. I/O points are wired up in parallel with any of the existing PLC that I want to monitor.
Here is a link to the Click with Ethernet:
https://www.automationdirect.com/clickplcs/hardware/click-cpu#standard-e

I would look at AdvancedHMI to pull the data from each of the PLC's. You will find that you could use some of the existing drivers on the units to communicate without purchasing any additional hardware for communications.
https://sourceforge.net/projects/advancedhmi/
This is free software that will run in visual studio. It was written in VB.Net and is open sourced.

Basic installation and communication from AdvancedHMI to BRX Modbus TCP.
http://accautomation.ca/create-a-plc-with-hmi-training-and-learning-environment-free/
Video:
https://youtu.be/1rWI-A-nZdo

Hope this helps you out.
Regards,

Click to expand...

Thanks for respnding.
Sorry, the Modbus is Serrial not TCP.


What do you think please?

aku agak2 mcm ni,

https://www.anybus.com/products/gat...cator/detail/anybus-communicator---modbus-tcp

For the Siemens device, if it is a 300 or 400 series, modbus rtu is going to be a nightmare.


I would look at each device you have and find the protocol that is the easiest to use. Then buy converters/gateways for those.

boneless said:

I would look at each device you have and find the protocol that is the easiest to use. Then buy converters/gateways for those.

Click to expand...

I second this and would simply add that you should buy two of each because those gateway thingies have an habit of going off market and you'll then have to re-engineer comms again.

boneless said:

For the Siemens device, if it is a 300 or 400 series, modbus rtu is going to be a nightmare.


I would look at each device you have and find the protocol that is the easiest to use. Then buy converters/gateways for those.

Click to expand...

If I use say, Siemens Modbus for sites with Siemens PLC, Allen Bradley Modbus for sites with Allen Bradley PLC, GE Modbus for sites with GE PLC etc, WILL THIS SOLVE MY PROBLEMS SUCH THAT I CAN TRANSFER DATA TO MELSEC Q-Series PLC/M2M RTU (soft)?

MODBUS is a standardized protocol, that is the beauty of it.

A Beijer X2 Hmi will act as a protocol converter from any of the brands mentioned in the original post to Modbus Rtu, acting as a master or slave, or indeed both.

paraffin power said:

A Beijer X2 Hmi will act as a protocol converter from any of the brands mentioned in the original post to Modbus Rtu, acting as a master or slave, or indeed both.

Click to expand...

OK,
But Mitsubishi GOTs has been selected for this project

boneless said:

MODBUS is a standardized protocol, that is the beauty of it.

Click to expand...

YES.

You are right bro, but in my case, can one particular make be able to pull data from the different PLCs to Melsec Q series?

boneless said:

MODBUS is a standardized protocol, that is the beauty of it.

Click to expand...

The name is standard, that is about it. lmao.





anyway, I would go with a red lion datastation to do the protocol conversions.

I agree on the Redlion, as it can handle serial modbus, Ethernet modbus, and Ethernet/IP.

I never recommend Modbus RTU. If you read the specifications you will find that Modbus RTU is very timing dependent. The problem I have had is that many manufacturers of Modbus RTU devices can't meet the timing specifications. The problem is more severe at higher bit rates. At 9.6K a character takes about 1 millisecond to send. If there is a gap of 1.5 milliseconds between characters or 1.5 character times, the next character is part of a the next message. Obviously both messages will fail the checksum test. There is also a 3.5 character wait time between sending messages. So how does one guarantee the timing of half a millisecond at 9.6K let alone 115.2K?

Modbus RTU timing is hard to meet if a USB to serial adapter is used.

I hate having to do the tech support for Modbus RTU problems when it is the other clueless manufacturers fault. My advice is don't use Modbus RTU or if you must, make sure all the devices pass this test.
http://www.modbus.org/certification.php