G940 Firmware

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RussDirks
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G940 Firmware

Post by RussDirks » Sat Jul 10, 2010 12:41 am

Logitech recently released a new firmware update that makes significant changes to the way FF is implemented. (Click here for instructions on how to update your firmware.) Some things are vastly improved, the most notable of which is the fact that they have managed to almost totally eliminate the "FF Gap" -- the area of no FF resistance in the center of joystick range. :D

There is one significant problem though (which fortunately has a work-around). They have made significant changes to what I call the "force response curve". What that refers to is the amount of centering force produced in response to a given software command (input value). For instance, if a software client like FS Force requests 100% centering force, the joystick drivers should set the centering force to 100% of the total force the joystick is capable of producing. If the client requests 50%, the joystick should produce 50% of it's maximum force, etc. I would refer to this as a linear response curve, which is the ideal -- it's very predictable; you know exactly what you're going to get. This could be graphed as follows:

Code: Select all

     100% |                              /
          |                            /
          |                          /
          |                        /
          |                      /
          |                    /
          |                  /
Centering |                /
Strength  |              /
          |            /
          |          /
          |        /
          |      / 
          |    /
          |  /
          |/
      0%  --------------------------------
          0%        input value        100%

Unfortunately, what Logitech has done is to modify the response curve, such that centering force increases very quickly at the beginning. By the time the input value reaches around 15%-20%, the centering force has reached it's maximum value, and further increases in the input value have no further effect. You could graph the response curve something like this:

Code: Select all

     100% |      ------------------------
          |     /                       
          |    /                      
          |   |                     
          |   |                   
          |   |                 
          |   |               
Centering |   |             
Strength  |   |           
          |   |         
          |   |       
          |   |    
          |   |    
          |  /
          | /
          |/
      0%  --------------------------------
          0%        input value        100%

What you will experience with this new firmware update is that the joystick will seem to be at full centering strength, no matter what airspeed you're flying at. You could be in a full stall, but the stick will be at maximum centering strength.

Fortunately there is a way to adjust this. Logitech provides adjustments in Control Panel / Game Controllers / Properties / Settings. If you adjust the "Spring Effect Strength" slider to values less than 100%, you are effectively straightening out the response curve, so it looks more like the top one.

Another way to improve things is to adjust the force curves in FS Force Profile Manager. Normally they look something like the one on the left in the image below. What you want to do is adjust them so they look similar to the one on the right. You should aim for approximately 5% centering strength at the aircrafts stall speed, and between 15% - 20% at max cruise speed.

Image
Last edited by RussDirks on Tue Jul 12, 2011 2:00 am, edited 2 times in total.
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Post by fm_weasel » Tue Aug 17, 2010 9:49 am

Hey Russ,

This is great info but I may not be smart enough to hone this calibration in on my own.

First, you say the spring effect strength should be less than 100%. About how much less?

Second, on adjusting the response curves. You say to start at 5% force around the stall speed of the aircraft, increasing to 15%-20% at max cruise. In your image above, it shows the force at 50% around 110kts, and 90% around 320kts... Where do you have it set at the 15%-20% range? I'm a little confused as to how my particular setup should look. I fly a single engine prop that cruises at 155kts IAS, stalls at around 60kts IAS with flaps.

Last, do you still notice a prominent slop in the center after the firmware update? It may have gotten tighter, but I still notice the stick moves a bit before the force effect kicks in.

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Post by RussDirks » Fri Aug 20, 2010 1:33 am

1. I don't have any specific recommendations, since this isn't the ideal way of dealing with the problem, I just mention it because it is less work than modifying all the FS Force profiles. Try between 75% - 80% and see if that softens the stick up a bit.

2. The image I have posted above is the way the graph should look for joysticks other than the G940. For the G940, the graph will look much flatter and lower.

3. For your specific airplane, edit the profile and adjust the first point of the graph to be at 60kts on the X axis and 5% on the Y axis. Set the second point at 155kts / 15%, and set the last graph point at Vne / 100%.

4. I found that the firmware update almost totally elimated the center slop. Of course you could never eliminate it all. Even real airplanes have play in the yoke.
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Post by fm_weasel » Sun Aug 29, 2010 2:51 am

Thanks Russ. I've played with this a bit and it has helped tremendously. Maybe you could offer a couple more pointers for me to iron out 2 remaining nags I have...

I think my elevator trim wheel is a little touchy. This may require me to adjust my trimming technique, but I was wondering if you had any suggestions on smoothing out that axis a bit? Seems like a unit of trim up/down is often too much correction, making level flight difficult to attain.

Secondly, after achieving what feels like straight and level trimmed flight, I find that there's just the slightest amount of wiggle room from the stick's centered position. This results in the stick leaning either slightly forward (very slightly, almost unnoticeable) or slightly backward. Regardless, this means that hands-off, even a properly trimmed airplane will quickly begin a prominent dive or climb. Can FSX or FSforce be adjusted to ignore this very little bit of initial input? It seems to just be the weight of the stick leaning against the force gears, causing a featherweight input, but it's just enough movement to get the elevator going. I understand that even in real life, a trimmed aircraft will begin to deviate from a straight and level state, but you can usually let it fly hands free for at least a minute before obvious correction is needed. In FSX, I don't even have time to take my hands off the stick and tune a radio before jumping back to correct an unwanted climb/dive of no less than 500FPM.

Sorry to unload these questions on you, I just figured you have the wisdom of experience, and you might have some easy answers for me. Thanks!

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Post by RussDirks » Mon Aug 30, 2010 11:44 pm

I think my elevator trim wheel is a little touchy. This may require me to adjust my trimming technique, but I was wondering if you had any suggestions on smoothing out that axis a bit? Seems like a unit of trim up/down is often too much correction, making level flight difficult to attain.
Start Profile Manager, go to Options / Trim Click amount. Type in a higher number to achieve finer control of trim.

Regarding your second issue, try increasing the null zone in FSX. That causes FSX to ignore control inputs near the center of motion.
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Post by fm_weasel » Tue Aug 31, 2010 10:41 am

Thanks Russ. I adjusted the nullzone and now have it set so that the aircraft will fly straight and level, properly trimmed, hands off. It was a lot of fun flying last night with this configuration.

Of course there's always a catch. It took setting the null zone to 65% before achieving this optimum setup. That seems like a really big chunk of my joystick's physical throw to toss out to a null zone. Does this sound typical to you or should I be looking into whether or not I have a hardware problem?

Thanks Russ, your continued advice is greatly appreciated.

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Post by crim3d » Tue Aug 31, 2010 4:08 pm

But the null zone only works at the physical center of the range of movement of the joystick, and when you trim the logical center does not coincide with the physical center.
The problem is that you can't have a null zone that moves with the center as you trim without losing range of the joystick or, in a trivial implementation, without having 'jumps' in the moment the null zone is updated to the current joystick position. (The truth is that it is easier to see with a graphic showing input vs output)

I have done a glovepie script that provides a null zone that udpates its position when I release one of the trim buttons, and makes a huge difference!! Unfortunately it's a bit complicated to setup and, as I said, I lose range of movement. But it's worth as you can imagine.

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Post by fm_weasel » Tue Aug 31, 2010 10:06 pm

I kinda see what you're explaining. I guess I assumed that trimming didn't really move the logical center, only decreased the amount of "pushback" the FFB gears provided (similar to how you perceive relieved pressure on a real aircraft's control yoke when trimming).

Anyway, the nullzone increase works well. I'd like to have more than 35% of the joystick's physical throw remaining to take up some of the sensitivity of the control surfaces, but it flies well enough as is.

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Post by StigAndre7 » Wed May 15, 2013 8:36 pm

I'm new at this. And feel like my brain is occupado with all other sim stuff...But here goes, could anyone be so kind to show me their G940 set up - so that I can tune it just the same. What I fly is B737 and learjet, mostly. And I should also mention that I use AccuFeel and EZdock add ons..

I also can not make a purchase. But I have sent a mail to support for that.

Im just unsure on what to do with my stick. Tried FS demo, and it was much more nicer than logitechs force feedback. And all the positive feedback from users made my choice easy. If anyone has any tips it is greatly appreciated.

Sincerely
Stig
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G940 Firmware

Post by wrap23 » Wed May 03, 2017 12:40 am

Realize this is an old thread but....

Looking at getting used G940. The logitech site no longer seems to have firmware update available (unless it comes as part of the driver package.) Is the logitech driver still viable in windows 10? Their site has a driver that implies it works on win10 64bit. Obviously, I don't want to buy a device I can't use.

My MS Sidewinder2 works without a specific driver but of course does not have the program-ability that it had in XP. Does the G940 work with a generic driver like the Sidewinder or does the Logitech driver actually work in Win10?

Thanks,
Don

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Re: G940 Firmware

Post by RussDirks » Wed May 03, 2017 6:30 am

My G940 works great under Win10. Can't remember if I actually installed the Logitech drivers or if Windows has them built-in. Regardless, I would have no hesitation installing the Logitech drivers.
My MS Sidewinder2 works without a specific driver but of course does not have the program-ability that it had in XP.
?? Not sure what you're talking about there. MSFF2 is also a great performer with FS Force. It is actually the joystick I recommend.
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Re: G940 Firmware

Post by wrap23 » Thu May 04, 2017 5:55 am

Thanks Russel

It is great to know the G940 works well under Windows 10. I love the build quality of the CH Products ForceFX but I want the dual throttle of the G940.
I stuffed the Sidwinder 2 board into my ForceFX and it functions well with your program. It does unfortunately suffer from a little center sloppiness that I guess is similar to the G940 until the Logitech firmware update.
I used the original 15 pin cable of the FX to carry the MSSW2 throttle axis to my old CH throttle. I used a Bodnar interface to convert my CH Throttle to USB and gain functionality of all the buttons. Works well, however it's hard to simulate an engine failure on a twin engine plane with a single throttle!

As far as programmability, I was referencing the sidewinder software that allowed profiles for various games. Not needed in P3D with your software.
Thanks for a great program and your continued support over the years. Seems like force feedback enthusiasts aren't a huge percentage of the simming community. Thank goodness you are!

Don

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