Mark VIe - Live and Initial Value


Thread Starter


We have 4 GTG (Frame 7E) and control is mark VIe. Can somebody explain me what are the live value and Initial value with some example would be great? And also their different layers of password for example admin etc please share your knowledge about them. Especially CSA.


There are (or at least there were) some extremely knowledgeable Instrument & Control Technicians at your site. Have you asked them for an explanation--using the HMIs at site would be much easier to explain this than with words on an Internet forum where we can't post snippets or .pdf's.

Also, there is help in ToolboxST for these kinds of questions. Have you looked at the 'Help' in ToolboxST? And, have you RTFM (Read The Fine Manual)--the Mark VI ToolboxST programming and configuration manual (NOT GEH-6721--that's mostly hardware-related; there are several other Mark VIe manuals devoted to software, programming and configuration)? There should be a Documentation folder under Programs and Files | GE Control System Solutions | Mark VIe or somewhere "nearby" with all of the manuals--and more--needed for the equipment provided at your site.

'Initial Value' is something which was added to ToolboxST that allows a programmer to define the "default" value which appears in the application code upon start-up, or when there is some kind of communication loss/error (this is where it's best to consult the manual(s) and the Help files). This is sometimes used for critical signals to "default" (fall back to; switch to)--again in the event of a communication loss/error, or during starting/re-booting. The signals I'm speaking of are signals which are usually driven by critical inputs (logic and real (T/Cs; pressure transmitters; LVDTs; etc.). But, GE doesn't use this method of "initialization" very often; it's something that was added to the "toolset" in ToolboxST because the Mark VIe is also promoted and used for BOP (Balance-of-Plant) and DCS (Distributed Control System) applications, and because other vendors/manufacturers have this capability it was added to the GE capability.

Control Constants all have 'Initial Values' also--the value of the Constant "from the factory" or when a permanent Control Constant change is made in the field.

The 'Live Value' of a signal is the actual, current value of a signal in the running application code. You won't see a 'Live Value' for any signal unless ToolboxST is connected to and receiving data from a Mark VIe. (If I recall correctly, 'Live Values' are displayed in green font, to distinguish them from other, non-changing values.)

Because you didn't say why you were interested in the differences between 'Initial-' and 'Live Values' I'm going to presume it's because of GE's poor practice of defining a Control Constant (which has, and must have, an 'Initial Value') and then over-writing the 'Initial Value' in the application code so that the Control Constant's value changes. It just infuriates people, who adamantly believe that a Control Constant value is fixed and doesn't change (like people who think the ground should NEVER move, but, earthquakes do happen--especially in your neck of the woods, Sardar99; right?).

So, for example, a Control Constant like FSRMAX is set to 100.00% using the 'Initial Value' when creating the Control Constant while configuring/programming the Mark VIe. But, if some engineer then creates some application code to modify the value of FSRMAX based on some criteria which causes FSRMAX to be different than the 'Initial Value' when someone is looking at the 'Live Value' of FSRMAX it can be different than the 'Initial Value.' (I'm <b>ONLY</b> talking about Control Constants is this example!) So, let's say the engineer wrote application code that reduces FSRMAX any time the unit is on CPD-biased exhaust temperature control (Base Load) to a value that is, say, based on shaft speed (TNH) and ambient temperature and the type of gas fuel being burned (natural gas vs. propane, for example). Because shaft speed isn't always EXACTLY 100.00% (it varies with frequency when synchronized to a grid, and grids are never exactly at 60.00 Hz (in Sardar99's part of the woods the grid frequency is stable, but it still varies around 60.0 Hz, just not usually very much). And, of course, ambient temperature changes throughout the day and throughout the year (though at Sardar99's site the ambient is generally considered to be some of the finest in the world and is very temperate). And the fuel--that also varies at Sardar99's site, too. So, therefore, when operating at Base Load the value of FSRMAX would be something other than the 'Initial Value' of 100.0%--but at <b>ANY</b>other time (starting, shutdown, slowroll, synchronizing, part load, preselected load) FSRMAX would be 100.0%. This just drives some people absolutely BONKERS. And, rightfully so--Control Constant values should remain, well, constant--correct? After all, it's part of the group of values they belong to: Control <i><b>Constants</b></i>, which implies they don't change (unless manually changed for some good reason. And, if the change is to be permanent, then the 'Initial Value' needs to ultimately be changed.

Now, if you're speaking about some other type of 'Initial Value' and 'Live Value' then you're going to have to be more specific--after you've had a read of the applicable sections of the Mark VIe programming and configuration manuals, and/or used the 'Help' available in ToolboxST.

As for 'Password Protection,' well--'Initial Values' can't be changed with at least Level 2 password knowledge (if I recall correctly). 'Live' Control Constant values can be temporarily changed, with Level 1 password knowledge (in the same way that Logic Signals can be forced with Level 1 password knowledge, again, if I recall correctly). But, to change an 'Initial Value' of any signal requires Level 2.

Hope this helps!