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We have frame 9E gas turbine for power generation with Mark 5 TMR control system.

We checked all the R, S, T & C status in LCC display. S showing A7, but C LCC display toggling between "A7" & "DCC ERROR."

Is there anything else we can check please?


If the processor is at A7, that's good.

What Diagnostic Alarms are displayed in the Diagnostic Alarm window for <C>?

Have you tried issuing a 'Diagnostic Alarm Reset' from the Diagnostic Alarm Display?

The Mark V Maintenance Manual has some sections on using the LCC/SLCC display and keypad to "interrogate" the processor, and to reset alarms. And, it has been described several times in different threads here on control.com. (There is a cleverly hidden 'Search' field at the far right of the Menu bar at the top of every control.com page. It's suggested you use the Search 'Help' because it's not intuitive--it's fast, but not intuitive.)

Just about any time someone uses 'CARD ID' it generates Diagnostic Alarms, and sometimes these alarms have to be reset using the LCC/SLCC keypad. It seems the Mark V designers realized late in the production life of the Mark V that having to reset some Diagnostic Alarms using the LCC/SLCC keypad was not convenient, so they enabled the operator interface Diagnostic Alarm Window's Diagnostic Alarm Reset button to do that. But, there's a lot of Mark Vs out there that still require the LCC/SLCC keypad to reset some--not all, but some--Diagnostic Alarms.

The LCC/SLCC keypad/display can also be used to indicate what some of the alarms are, but you have to write them down.

DCC/SDCC alarms can occur if there is a malformed request for data from the operator interface (which can happen a LOT from many GE Mark V HMIs--the ones that run MS-Windows and CIMPLICITY), and occasionally from <I>s as well, especially if the <I> is used for MODBUS communications (sometimes the MODBUS master can get confused and not ask for data or get "backed up" with data requests), and these can cause the dual-ported RAM in the DCC/SDCC to annunciate alarms.

If it continues happening, then there may also be something wrong with the StageLink cable, or one of the ARCnet cards. Some of the BNC-tee connectors have also bee known to not be for ARCnet (they were Ethernet BNC connectors, which seem to work for a while, and then "die"). Corrosion has also been a problem at some sites where the atmosphere isn't the best. Finally, the BNC terminating resistors have been known to go bad for no apparent reason. But, usually, problems can be traced to poor/bad BNC connectors on the coaxial StageLink cable. (Also, some sites used the wrong coaxial cable--Ethernet instead of ARCnet--which also seems to work for a while, then develop problems.)

But that's the usual culprits. Again, have a read of the Mark V Maintenance Manual, GEH-5980, for information on using the LCC/SLCC keypad/display for clearing alarms, and for interrogating the processor to see which cards are NOT at A7, etc. It has limited uses, but sometimes they can be helpful.

Hope this helps!
but "C" S LCC display toggling between "A7" & "DCC ERROR." and the parameter operator interface <I> is bloqued.

<b>Note</b> not sure what bloqued is. Maybe blocked?

The good news--again--is that <C> is at A7. That's good.

Are you saying that the <I> is not communicating with <C>?

That's most likely a StageLink problem, or an ARCnet card problem, or it could be a problem in <C> (the TCCA).

Or, by using the LCC/SLCC display keypad you can discover what the Diagnostic Alarm is. Most likely, it's going to require at least one re-boot of <C> (I know; no one likes to hear that, but we don't have enough information to be of more help). And, if you have to replace a card, that's going to require you to power down <C>.

You can reset the Diagnostic Alarms--if possible--using the LCC/SLCC display. You have to refer to the Mark V Maintenance Manual for details of which keys to press and what to do. There are seven (7) possible displays which can be accessed; I believe the third of the seven is the one that allows you to reset the alarms, and displays, in a rolling fashion, the alarms. I don't have access to the manual at this writing.

You need to ensure the StageLink is working correctly. There are LEDs on the ARCnet card which should be blinking to indicate communications. There are software utilities (ARCWHO, if I recall correctly) which can be run from the command line of the <I> to interrogate the StageLink to see if it can find any nodes (<I>s; Mark Vs). Have you tried any of them?

<i>If the unit was configured correctly,</i> re-booting <C> when the unit is running <b>should NOT</b> cause any problems with unit operation. But, not all units were configured correctly (AND, I'm presuming you are working on a TMR Mark V turbine control panel).

This is about all the help I can provide, based on the information provided. You're going to have to try to figure out if it's a <C> problem (which will most likely require a re-boot--at a minimum--to investigate/resolve) or a StageLink problem (cable; connector; ARCnet card; etc.). Have you tried re-booting the <I>?

When you write for help with problems like this, it's best if you tell us as much as you can about the site, the problem, when the problem started, what's been done to try to troubleshoot the problem, and what the result of the troubleshooting were. It's frustrating for both of us if I recommend things you've already done but haven't told me. Remember--we're NOT there with you. We ONLY know what you tell us. The MORE you tell us, the more concise the replies will be.

And, don't be afraid to use the Mark V manuals--there really is some useful information in there. (It's just hard to find sometimes.)

Please write back to let us know how you fare--and if you need more help, we need more information.

There is no ARCnet "card" in the Mark V. The StageLink cable connects to a BNC connector on the card in Loc. 6 of <C>. There is a cable that connects the card in Loc. 6 to the TCCA and then to the DCC/SDCC and LCC/SLCC.

This is all shown in drawings in the Mark V Maintenance Manual, GEH-5980.

There are two (2) BNC connectors on the card in Loc. 6 of <C>. It doesn't matter which BNC connector the StageLink cable is connected to. (I'm presuming there is only one Mark V, and there is no EX2000 exciter; so there's only one StageLink cable to be connected to <C>.)

Are the LEDs on the ARCnet card in the <I> blinking? Is it trying to communicate?

Did you recently replace the DCC/SDCC and/or LCC/SLCC card(s) in <C>? If so, did you set the correct StageLink ID using the LCC/SLCC keypad?

I think it's time to get someone to site who can help you troubleshoot this problem.