How to use an ION7650 as gateway with COM1 and COM2

[Jérôme]

Hello,

I'm currently working on a project where we have an ION7650 with COM1 and COM2 used to communicate on Modbus ports. On each port, we have Modbus slaves such as SEPAM relay or Micrologic unit. The ION is connected to an Ethernet network.There is a PMS system as well which has to communicate with the Modbus slaves connected to the ION ports.

I'm wondering if we can use Ethergate mode for the PMS system to be able to access the Modbus slaves or do we have to use a PME like software to use this feature?

I'm asking this question because I'm trying to reach the Modbus slaves through the ION using Modscan but it does not work so far... I set up the ION to have both ports as Ethergate and I send requests to ports 7801 or 7802 as specified in the documentation.

Thanks in advance for your help.

Regards,

Jérôme.

[Bojan]

Hi Jerome,

I think you should set up ION to have a port as ModGate and use port 502 (RESL198534 - FA212220.en_US 2.0)

Best Regards,

Bojan

[Hal_Etheridge]

It is possible to use ethergate like a pass through gateway - the master software needs to generate a ModRTU protocol request on a TCP connection.

I do NOT recommend you do this however.  The ModTCP protocol is specifically designed to handle out of sync and other communication issues common with TCP connections.  If you use ModRTU all these safety mechanisms are not present so you have a fairly good chance of getting undetectable bad data from the device periodically.  This will make the system unreliable.

As Bojan mentioned, the best solution is to either use a dedicated gateway like EGX or use the ModGate feature of the ION devices to act as your gateway.

[Jérôme]

As you mentioned Bojan, I can use the Modbus Gateway feature from the ION. The main drawback I see there is that I can only use one COM port to put all the slaves and for the moment the plan was to "split" the slaves between COM1 and COM2. This could be anyway the best solution.

From what you explain Hal, I understand that I need a Modbus RTU over Ethernet test software and it seems that Modscan cannot be used for this purpose. Am I correct or am I missing something?

Regards,

Jérôme.

[Hal_Etheridge]

Anything that can generate ModRTU requests over a TCP connection should work.  This is not a very common feature though so I am not surprised that ModScan does not support it.  This configuration is definitely not recommended unless you have no other options - you *will* get corrupted data periodically.

If you are just wanting to test it out then you can use a small modbus master test application included with PME.  "mbmaster.exe" is located in the system/bin with the other PME binaries.  Not formally supported but it allows you to generate arbitrary requests to a modbus slave to get the raw data back.  Good for verifying comms and to quickly find the raw values for modbus registers.  Mostly we use it during debugging the drivers and included it in the release as it may be useful to SI/AppEngrs when debugging difficult problems in the field.  Note that this is a commandline tool so it is not the most user friendly of interfaces but it is extremely basic.

[Yu_Diao]

I used to use "ModbusPoll" which is similar to Modscan but does support ModRTU over TCP, you can give it a try.

Also, beside the "mbmaster.exe" mentioned by Hal above, if the meters you want to read registersrom are supported in ION Setup, ION Setup should automatically switch to ModRTU over TCP when the port number are 7801, 7802.

[Jérôme]

I finally made tests with "mbmaster.exe" and it worked fine. I could find it in a Schneider Electric FAQ : http://www2.schneider-electric.com/sites/corporate/en/support/faq/faq_main.page?page=content&country...

So at least I know that my setup is correct in the ION meter and that the Modbus lines are good.

Thanks all for the support.

[Hal_Etheridge]

Great that things are working.  Note that the mbmaster.exe tool is meant as a test tool only.  It uses exactly the same low level code as PME does so it should support everything that the PME modbus drivers do (and then some).  If there are any function codes or other features missing you would like to see added please let me know.  It can be hard sometimes to understand the detailed requirements for certain things like commissioning.