Com'X with two separate Modbus TCP masters

[solutions_iems-]

I have a landlord/tenant sub-metering installation that uses PME v7.2 and EGX100 for the Landlord PMS. The tenant now wishes to see his meters on a separate system (BMS) but does not want to connect to the PMS due to network security protocol requirements.

Can I replace the EGX100 with a Com'X200 and configure each Ethernet port with a different IP address, allowing both the BMS & PMS to poll data from the connected Modbus meters?

[michael_franz]

Iain:

I have not tested this but it should be possible.  Make sure you check the device compatibility list with any ComX to insure that it supports the device you want to use.  I would like to use the ComX 510 as a Poor Mans PME.  Unfortunately the ComX family does not have support for some legacy devices.

[solutions_iems-]

Michael

Thanks for the reply. The power meters are 3rd party custom devices of IME and Selec manufacture. This does not matter as the Com'X will be acting as an Ethernet gateway to PME, where the meters have already been created in Modbus Device Importer and it is not my responsibility to integrate them into the BMS 🙂

[michael_franz]

Iain:

As long as it a standard Modbus device with standard setting it should work.  Have not tested this yet myself.  I have a Com X 510 in my home lab.  Your question has me intrigued.  Another way I have done this is by adding an EGX that has been set as a serial slave to the BMS.  This is proven and works well while maintaining your security.

Michael

[Anonymous user]

Hi Iain,

I hope you're doing well. In order to provide the most accurate response for you, can you answer some questions for me:

• You mention configuring both ethernet ports with different IP addresses. How will these IP's be assigned (are they static / dhcp?)
• Will the IP Addresses share a common gateway?
• How are the Modbus devices connected (RS485, Ethernet, etc)?

Best Regards,

Colton Peltier

[michael_franz]

Colton:

What I read into this was that the site has one network with PME and a BMS network that is separate.  It is a security concern with the customer.  Typically they would be fixed IPs so the gathering device or software has a fixed reference.  Since Iain wants to replace an EGX with a Com X I assumed the devices were serial below the EGX.

I have not tested if each Com X both Com X ports could view data via Modbus TCP/IP on two networks.

One concern is that BMS systems tend to have a high sample rate that can overwhelm the RS485 network.  Many default at 350ms and some field people do not know how to slow this down.  Too fast of a scan can cause both the BMS and PME to fail on communication to devices on the serial side.

Hope that helps.

Michael

[Anonymous user]

Hi Michael,

That certainly does help, thank you for the additional information. I have requested the above information as well from Iain, so I can vet the setup he is considering here in lab to give him a definitive answer on his desired architecture.

Thank you and Best Regards,

Colton Peltier

[michael_franz]

Colton:

Legacy drivers for Com X 510.  We need legacy drivers.  Most stuff is written in XML or some common format.  Tell us how to make the drivers and tell us it is at our own risk.

Michael

[solutions_iems-]

Colton

To clarify:

The building has PME v7.2 for the PMS. It also has a separate tenant BMS. The two cannot be on the same IT network for security reasons.

The tenant wants to see the tenant meters on the BMS, as does the landlord but on the PMS.

There are 13 no. Modbus networks, each connected to an EGX100 that sit on a dedicated landlord IT network.

On each Modbus network are a mix of IME CE4DMID01 and Selec MRJ4M power meters.

In answer to your questions:

The Ethernet ports of the Com'X will be static IPs

The IP addresses do not have have a common gateway (I can see this being an issue with Com'X)

The Modbus devices are all serial (19200, no parity)

Thank you

Iain

[solutions_iems-]

Michael

Could this solution be used with 13 no. Ethernet gateways, connected to 130+ Modbus power meters?

Would the look-up table on an additional EGX100 be too big for the BMS to handle over the RS485 serial connection?

Thanks

Iain

[Anonymous user]

Hi Iain,

Thanks for the prompt response and additional information.

There is currently a known issue with the ComX that only one of the ethernet ports at a time can be configured as static. This issue is scheduled to be fixed in a firmware release in Q2 next year (2017). It is possible, however, to have one port set as static, and the other as dhcp. I'll do some testing for you to verify if the ports can have different gateways or not (I'm not 100% sure off the top of my head). Would it be possible to have one of the ethernet ports configured by a dhcp server?

Best Regards,

Colton Peltier

[michael_franz]

Iain:

One Link 150 will handle 16 IPs and 128 devices as a serial slave to other gateway redirect.  With most BMS I have worked with they would not be interested in that many devices.  Most look at the main and a few feeders.  130 + devices is a lot.  Two Links could handle it.  Just be sure the requests are slow, like once ever few seconds so PME and the BMS will be able to collect data.

Michael

[solutions_iems-]

Michael

There are 130+ tenant meters on site and the client wants them all. Fortunately, the information required may be just limited to real energy (kWh).

Do you have an example of a look-up table that you could send for reference?

Thanks

Iain

[michael_franz]

Iain:

Go to Link Gateway that will slave to BMS.  See attached for detail.  Simple great concept that I have used

for years.

Michael

[solutions_iems-]

Hi Michael

I'm afraid that I cannot see the attachment. Can you email it to solutions@iems-ltd.co.uk?

Thanks

Iain

[Eddic]

Hi Michael,

I have same issue as like this subject.

The Link gateway is serial device to the BMS, what if the BMS needs the TCP connection ?

Can using the Com'X device or using another Link gateway to adopted the serial to TCP one more time ?

Regards,

Eddic