Mark V IO.ASG Question

Greetings to the forum. My name is Michael and I'm a newbie to GE controls particularly the Mark V.

I've done some work over the years with various instrumentation, controls, and PLC type systems so I'm not totally green. For about a year now I have been working in the power generation industry, notably a combined cycle power plant utilizing one GE 6FA type gas turbine. Having never seen a Mark V system, I have been spending quite some time trying to understand how it all operates under the hood. I've been reading the manuals: User's, Maintenance and Application as well as trying to decipher the unit specific files on the HMI. I've also been perusing through quite a number of posts on this site of which there is a wealth of knowledge and quite obviously intelligent folks. I have many questions and I've searched the site and did not find exactly the answer I was looking for and please forgive me in advance if the answer is here and I just simply overlooked it.

At the moment I'm trying to wrap my mind around signal addressing, naming and basically the overall marriage of signals to physical I/O. I've been digging around in the TC2KREPT, IO.ASG, CSP and other files trying to piece together exactly which signal goes to what termination board and from there to what board in the core. I've come across termination boards with wiring landed to certain I/O of which I can't locate anything defined in any of the aforementioned files. Am I right in the belief that if there is nothing noted in the IO.ASG file that there is nothing configured in the Mark V for a particular input or output? Also are there non configurable I/O in some of the Core units such as with a P Core and items landed on the PTBA termination board? I was searching for the E-Stop and ETR signals in the various files that land at the P core and could not find them and thought that perhaps they had a fixed function and operated independently from any configuration.

I'll leave it at that for now. Any help with my questions and any advice as to how to tackle learning the Mark V is greatly appreciated. Thank you all for the great threads here.

Good questions, and as with all things Mark* there are answers and there are exceptions to answers.

If you've been reading threads on this forum you already know: There is no tool on the operator interface to "match" TC2KREPT.TXT and IO.ASG. AND, that TC2KREPT.TXT is an ASCII text file which was created at the factory well before the unit was shipped. FURTHER, if any changes are made to IO.ASG--either at the factory, or in the field--the person making the changes should have made any relevant changes to TC2KREPT.TXT. Sometimes that person does make the changes; quite often not. And sometimes, someone notes the differences and makes the changes later.

>Am I right in the belief that if there
>is nothing noted in the IO.ASG file that there is nothing
>configured in the Mark V for a particular input or output?

I don't have any Mark V unit-specific software to refer to at this writing, but if I recall correctly every input or output to the Mark V is "listed" in TC2KREPT.TXT. By "listed" I mean that every input channel and output channel terminal board point is listed in TC2KREPT.TXT. And, in the software column the CSP point name for the input or output is listed. And, if I recall correctly, that includes the E-Stop P/B circuit.

But, read on ....

>Also are there non configurable I/O in some of the Core
>units such as with a P Core and items landed on the PTBA
>termination board? I was searching for the E-Stop and ETR
>signals in the various files that land at the P core and
>could not find them and thought that perhaps they had a
>fixed function and operated independently from any

Good catch on this one. In early Mark V units, the primary speed pick-ups were shown in IO.ASG. BUT, what wasn't known at that time was that the CDB signal point name for speed <b>HAD</b> to be TNH (later it because TNH1 on some units). And, some cheeky field personnel decided they didn't like that signal point name and they changed it in IO.ASG--because the could. And, then, the unit had problems--REAL bad problems. And, they were eventually traced to the changed signal point name. SO, the primary speed pick-ups were eventually removed from IO.ASG.

Another group of inputs that HAD to have specific CDB point names were the flame detector inputs: FD_INTENS_n. And, I believe it was at the same time that the primary speed pickups were removed from IO.ASG these were removed as well--to prevent people from changing the names.

[Many blocks in the CSP REQUIRE specific inputs to have specific names--or, rather, the blocks expect specific inputs to have specific names is probably the more correct way to say it.]

I believe there is one more group of outputs that kind of falls into this category of not being listed in IO.ASG, but they are listed in TC2KREPT.TXT, and that's the <C> mA outputs. I think those outputs are "assigned" in MAOUT_C.SRC, not in IO.ASG--but again, I don't have and Mark V unit-specific files to refer to at this writing.

PTRs and ETRs--those are the names of the redundant relays on the TCTG that are driven by the <Q> signals and <P> signals, respectively. I don't ever recall seeing them (identified as PTR or ETR) in either IO.ASG or TC2KREPT.TXT. You need to find the relevant Figure in Appendix D of the Application Manual, GEH-6195, to see how they work together to allow a trip solenoid (20FG-1 or 20FL-1, for example) to be energized, or de-energized.

Now, for the E-Stop P/B inputs. Again, you need to find the appropriate Figure in Appendix D of the App. Manual to understand how this works. The name of the figure should be "<P> Core - Emergency Trip Pushbutton Connections on PTBA." You will see that when the E-Stop circuit is closed (continuous) there are four relays that will be energized: 4-1, 4-2, 4-3 & 4-4. And also on the page you see a "two-out-of-four" diagram of the contacts associated with the four relays that feeds power from P24VR power bus to the P24VR-4 power bus, and this P24VR-2 power bus is necessary for the PTR- and ETR relays to be energized by <Q> or <P>. And, if the E-stop P/B circuit is broken (by pushing any E-stop P/B, or if a wire comes loose in the circuit). then the four "4" relays (4-1, 4-2, 4-3 & 4-4) will be de-energized, which will then de-energize the PTRs <b>AND</b> the ETRs, which will de-energize the trip solenoid and the fuel stop valve(s) will close.

A little tip: Take a wide red or black marker and cross out all the TCTS and TCTL sheets in Appendix D (EXCEPT for the figure titled "<P> Core - Circuit Breaker (52G) Close Circuit)--they will cause confusion late at night when you are trying to troubleshoot some problem if you don't. Guaranteed.

Actually, we have to thank the sponsors of, the owner(s) of and the Kind Moderators of for the wealth of information available here. Without them the knowledge available here wouldn't be (available here). They make it possible for people to ask questions and share information.

Hope this helps! Some things with Mark* controls are intuitive, and some aren't. Again, good questions.
WOW!!! I made a TON of typo's in the above response.... I didn't use the 'check and preview' (rather I scrolled through the message in the editor and, obviously, didn't catch multiple errors.

My SINCEREST apologies for any confusion--hopefully it's not too mangled to make sense of.

Thank you very much for your reply and I appreciate your advice. I was truly hoping you would respond as it seems that almost every Mark V post I've read here had your input. I apologize for not getting back sooner, been away from the computer. I'm certain I will have many more questions the further I go down this rabbit hole but I will definitely dig through the forum before posting.

Hope this finds you well and thanks again.