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Does the MKV HMI act as a slave to the DCS?
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Does the MKV HMI act as a slave to the DCS?

If another HMI is connected to the MKV panel, can the turbine data be accessed by an application using MODBUS protocol over a serial connection?

What other ways can the turbine data be accessed by an application?

By Radhakrishnan on 11 February, 2009 - 6:08 am

Mark V HMI can be configured as MODBUS slave. Depending on the interface supported by the MODBUS master, COM port or Ethernet port on the HMI can be assigned for this task.

The other method of communication is through Cimplicity OPC server.

Just to add, u can also use GE GSM protocol to connect to your DCS. This is the case in our plant. We have Foxboro IA DCS.

I have 2 questions:

1) Do u have any reference doc to use Ethernet port for Modbus instead of COM port? This is barely described in GE's document.

2) What version of Cimplicity should be used in order to have this OPC server feature? we have cimplicity 4.0 running on Win NT 4.0

I was looking for a way to take turbine data from the HMI. The manual for the <I> says only one serial MODBUS connection can be used for each <I>. I thought the HMI might have a similar setup. The HMI I will be working on has a serial connection to the DCS.

There can be more than one <I>, or HMI, for each MKV panel, so I was wondering if I could connect to another instance of the <I>, or HMI, that isn't connected to the DCS. This would be done via serial MODBUS or MODBUS TCP to collect the turbine data that the MKV panel sends to the <I>/HMI.

Anyone have any suggestions?

By Adriel Michaud on 12 February, 2009 - 2:44 pm

Direct OPC access to MarkV's can be had with MatrikonOPC's OPC Server for MarkV Direct:

Connectivity through GSM can be done via the OPC Server for MarkV/VI GSM:

Adriel Michaud


Without our giving personal contact information to Matrikon (and Matrikon *WILL* contact those who do, repeatedly), we can't get access to the white papers published about how Matrikon's direct access to the Mark V works or what all of it's capabilities are.

A Google search revealed this:

The above is helpful, *BUT* this is absolutely *NOT* a replacement for the <I> or a GE Mark V HMI. One can't calibrate LVDT feedback or view the Prevote Data Display or change Control Constants or change sequencing or I/O configuration, etc. There are only a couple of non-GE solutions which can do this. I think you should be clearer about this on your website and when proposing this on Many people here are looking to replace their operator interfaces with something that doesn't still rely on an <I> or a GE Mark V HMI for basic troubleshooting and maintenance functions which the Matrikon option doesn't provide.

I don't want to belittle what Matrikon has done with their products for the Speedtronic turbine control systems. It's an excellent way to get gobs of data at a very fast rate without having to go through a GE mark V HMI (because I don't think the OPC option will work through an <I>), but it doesn't replace an <I> or a GE Mark V HMI. It will still be necessary to maintain and support an <I> or a GE Mark V HMI for basic maintenance and troubleshooting features.

And that's a very important distinction which should be made clear when considering this option. If all you want is data and control, this is a great option. But, if someone is looking to replace their <I> or GE Mark V HMI, this isn't going to satisfy the requirement.

If I'm wrong, please point us to some documentation which tells us otherwise (without having to provide contact information). Or, at least tell us what this can and can't do, because it's just not clear from the several posts Matrikon personnel have made here or on the website.

The old <I> operator interfaces could have multiple RS-232 MODBUS connections. I don't know what the HMIs are capable of these days, because I think it depends on whether or not TCI or CIMPLICITY is being used as the "driver" for the MODBUS communications.

I'm not a MODBUS expert, but for serial communications, isn't there RS-422/485 multi-drop mode? Or is there the 'only one Master' limit thing going on with that?

You could definitely have more than one GE Mark V HMI connected to a StageLink gathering data from a single Mark V. But, they aren't cheap. And to get one additional MODBUS connection it would seem to be a very expensive option.

And, there are other alternatives to GE Mark V HMIs. You could go to the Matrikon OPC site; they have advertised they can talk directly to Mark Vs and "supply" OPC data from their OPC server. There's also CSE Engineering's offering (search A couple of others have said they have Mark V-compatible interfaces, as well, on

By Radhakrishnan on 13 February, 2009 - 2:55 am

The use of COM port or Ethernet port depends on the type of interface the DCS has. Many of the DCS interfaces support only RS-232. If the interface is RS-485, an external 232/485 converter is required.

Cimplicity 4.0, to my knowledge, doesn't have OPC option. However, you can use an external MODBUS/OPC converter to interface through OPC. Cimplicity 5.5, which we have on some HMIs have OPC capability.

One of the problems you may face in using the TCI MODBUS interface is that the HMI, at times could get hung up. Also, keep in mind that only one option - COM or Ethernet port (not both) on the HMI can be enabled for TCI MODBUS communication

Using the OPC interface is a better option. However this will require an upgrade of the TCI as well. You need to check with the vendor.

I was looking for the way that to take turbine data from the HMI to DCS using Modbus communication.

> I was looking for the way that to take turbine data from the HMI to DCS using Modbus communication.

Have you tried OPC for this? MODBUS is no longer the preferred method of communicating with GE turbine controllers. Here is a link to learn a bit more about what OPC can do for you:

Let me know if you have any questions.


We have Mark V Control system connected to ABB freelance2000 DCS System through Modbus serial port. please explain how it connect.

what is the difference between PACKED, LOGIC?

The Mark V Speedtronic Application Manual, GEH-6195, has some very good information and explanations of Mark V MODBUS. While some of the information is particular to <I> operator interfaces running IDOS, the basics of how signals are configured don't change.

Also, GEH-6720, the Speedtronic HMI Manual, also has some useful information about GE Mark V HMIs running MS-Windows and CIMPLICITY.

The only reference I have is the 6195D Application Manual. This details the serial MODBUS connection from the <I> to the DCS.

Don't know anything about Cimplicity.

Okay; I'm beginning to understand. In the GE Mark V system, an <I> is not an HMI. (Isn't this FUN?)

An <I> is a Mark V operator interface, which to most people is the same thing as an HMI (Human Machine Interface). But, in the GE Mark V (and Mark VI, and Mark VIe) systems, there are HMIs, which are MS-Windows based PCs, running CIMPLICITY and some other programs. So, an <I>, while technically an "HMI", is not a GE Mark V HMI (which is usually the distinction you will see me make when referring to the "HMI" of a Mark V system.)

An <I> absolutely *can* have multiple RS-232 MODBUS connections, depending on the number of serial ports the CPU has. GE used a serial port expander card, made by Digiboard, that had eight (8) serial ports which could be used for additional RS-232 MODBUS ports if more than two serial ports were required. In the <I>, one serial port was typically used for the CPD (Cursor Positioing Device, the mouse or trackball), and the second one was used for a MODBUS port if necessary. If additional RS-232 serial ports were necessary, then a serial port expander card was provided.

The configuration of the serial port expander ports is described in the Mark V Application Guide, GEH-6195. It's done using F:\IO_PORTS.DAT.

So, I'm more than a little confused about why you think the Mark V App. Manual says only one serial MODBUS port could be configured on an <I> CPU. It only shows one example, using the second serial port of the CPU, S2. (Of course, it will require an ISA bus serial port expander card, and I would recommend trying to find a Digiboard model, perhaps from Gas Turbine Controls, one of the advertisers here on that makes this forum possible!).

GEH 6195D Application Manual, 10-4.1:

"Each <I> processor can provide one point-to-point MODBUS RS232 serial link to a customers DCS. Multiple MODBUS serial links from any one <I> are not possible."

I realize there is a difference between an <I> and an HMI. I am creating an application that will use MODBUS protocol to retrieve data from either an <I> or an HMI. Since I'm sending a MODBUS request, it shouldn't matter what's on the other end, be it an <I> or an HMI.

If I were to communicate with an <I>, I would first need to set up the port in IO_PORTS.DAT, like you said.(But the statement I mentioned in the Application manual was confusing me.) Then I would need to read the MODBUS.DAT file to find the location of the data I want to read. Send MODBUS command, <I> sends response, recieve data. I hope.

Now, if I were communicating with an HMI... Lost. Don't have a manual to help. I definately don't fully understand the HMI, but I was looking for similarities in the way the MODBUS communications are configured. If I send a MODBUS command to an HMI over a serial connection, will the HMI send a MODBUS response? Is there a file that maps the MODBUS register on the HMI?

There are certain MKV tags I want to retrieve from the interface I will be communicating with. In this case, it will be an HMI.

As was said before, depending on the vintage of the GE Mark V HMI, the OS, and the version of CIMPLICITY (isn't this fun?) MODBUS communications can be done through the TCI (Turbine Control Interface) service or through CIMPLICITY (but I don't think through both).

MODBUS would still be configured using MODBUS.DAT, the mapping of registers and coils and data points, etc.

You will need to get a copy of the HMI Manual for the GE Mark V HMI you will be using.

I can't comment on the statement you are referring to in GEH-6195. I know of at least two sites which had multiple MODBUS links to <I>s using the Digiboard. It's been a long time, though I don't recall if both MODBUS "ports" were communicating with one panel, or if each "port" was communicating with an individual Mark V panel. That may have been the critical difference.

Again, I was hoping that some MODBUS "master" here on could comment on using RS-422/485. Couldn't a converter be used to have multiple masters requesting data from a single slave? (I wouldn't recommend trying to get lots of the same data at a very high rate with both masters.) I'm not a MODBUS guru by any stretch of the imagination, so I may be way off base here.

I think you might also try posting on with the converter question. Also, you might try another thread on with this specific question. Sometimes, people just pass by a thread based simply on the title.

I would believe if the HMI were a GE Mark V HMI, you could implement a MODBUS Ethernet connection, but I don't know if TCI or CIMPLICITY or both support that.

The following link may offer another option:

Matrikon seem to have a version that runs "through" a GE Mark V HMI, and a version that runs independent of a GE Mark V HMI. I don't what it costs, but you were talking about adding another GE Mark V HMI, and that would still be a pretty expensive way to get more data via MODBUS. Which doesn't have any time stamps, or alarm and event data, which you could get from an OPC server.

I think there is at least one other OPC company which also has some version of a GE Mark V HMI OPC server (Kepware, perhaps?).

If you could tell us what software is installed on the HMI you will be using and provide an email address, perhaps someone could send you an electronic copy of the GE Mark V HMI Manual. I believe there is even a GE HMI MODBUS Manual that's been talked about in other threads on

By Radhakrishnan on 14 February, 2009 - 12:31 am

Please post your e-mail id. I shall send you step-by-step details.

if u're looking for OPC server which connects DIRECTLY to Mark V's Data Highway using GE Stagelink protocol, u've plenty of choices namely:

1) GCI from Global Controls
2) TMOS from ITS
3) IBECS from CSE Engineering
4) Direct Mark V OPC Server from Matrikon OPC
5) Direct Mark V OPC Server from Prism System

hope this helps.

I'm not looking for an OPC server, but taking data from the Stage Link system would be another way of retrieving the data we need. The <I> manual I have says the Stage Link system uses ARCNET, is that still being used? If anybody has information on how that works, I would appreciate it.

The GE HMI manual would be a tremendous help as well. I'm sure it has some good information.

Thank you everyone for the help.

The protocol and configuration of the Mark V StageLink is proprietary. GE designed it and owns the rights to it.

Others have reverse-engineered the protocol to develop products of their own, and are probably not likely to share those efforts without lots of legal paperwork and some compensation (probably a lot of compensation).

StageLink communication is based on the ARCnet protocol and topology.


I am new to and I hv not read the whole thread but I know one manual in GE "GEI-100517_modbus_HMI". THis describes different types of modbus configurations for GE-HMI applications.

Yes the MkV is a slave to the DCS via Modbus serial connection.

I know that both Global Controls and CSA have an interface to the MkV that is not associated with GE.

By Ronald Anderson on 5 June, 2009 - 11:47 am The Global Controls Interface (GCI) is a high speed replacement to the GE <I>, <G> or <HMI>. It communicates via the arcnet or alternative means. You don't have to remove your GE <I>, <G> or <HMI> off the arcnet until you are confident in the new interface.

The operator interface has an integrated historian. The strength of Global Controls Interface (GCI) is its parallel software protocol architecture, increasing overall HMI reliability/availability.

The GCI software architecture allows the operator to take the Proficy/Historian, Cimplicity HMI, or DCS interface offline without interrupting the flow of data or turbine operation. The GCI supports current DCS interface (ModBus Serial, ModuBus TCP, GSM). The GCI communicates directly with the MKV without using TCI, it has its own communications protocol. But there are some real benefits that will blow your mind over the OEM product. You must watch the videos to see the real power unleashed.

See the website, feel free to contact me 24hrs a day 7 days a week to talk about it.

By Ronald Anderson on 8 February, 2012 - 6:11 pm

Ronald Anderson is now employed by Advanced Turbine Controls,

If I can help any client, technician or engineer, please do not hesitate to contact me at or to view my qualifications on the topic of GE Speedtronic Turbine Controls, whether it be from the MKI, MKII, MKIII, MKIV, MKIV+, MKV, MKVe, or MKVI or the GE OEM mechanical hydraulic controls (MHC) or Woodward 505 systems.

I have over 24 years in the turbine controls industry primarily with General Electric turbines, all frame sizes and combinations of control platforms.

I am here to help and serve.