SIOC script for the Brake Pressure gauge with servo?

[HondaCop]

Does anyone have a SIOC script for the Brake Pressure gauge with a servo? Thanks in advance.

[Geremy Britton]

Hi, Ian has some stuff about this on his webpage, he might have something useful there. I'm not sure though.

http://www.737ng.co.uk/help.htm

[fordgt40]

Hondacop

I think that Geremy might be referring to the Brake Pressure gauge that I built and the piccies are on Ian`s site.

Sorry, but I have not yet written any code - I just used the IOTEST programme to check that it works. Perhaps this could be a good first project for you in using SIOC :p. You will never find a totally suitable example, so it is inevitable that you need to learn the syntax and use of SIOC texts and .ini files.

Regards

David

[Geremy Britton]

ah it's your work. Excellent guage, David. How do you manage to get the servo to work and to stop at the top (ie, max brake pressure) and not continue round and round the guage.

I'm pretty much an amateur when it comes to the servo and motors side of things so could you give me some tips about that side of things if you wouldn't mind. Because it would be great to link it up to the park brake for example and the brake press guage moves up slightly.

Thanks


Gez

[HondaCop]

Hi David! That is a nice looking brake pressure gauge indeed. Job well done!

Like you guessed, I do have the gauge finished and hooked up. I just need to write the SIOC script for it. I already have a working SIOC script for the Flaps Indicator with servo, so if I can find out the offset from which I can pull the brake pressure data from, then I can write a script for it by using the flaps script as a template on how to begin.

Any idea which is the offset? I looked at the FSUIPC offsets and I couldn't see any that references brake pressure. Do I need to do some calculations with other offsets which will give me a brake pressure reading? Or is it an avionics offset which maybe SimAvionics already has available?

Thanks for any help!

[fordgt40]

Geremy, Hondacop

Thanks for your kind comments.

Geremy

An unmodified servo will only travel about 180deg and by using the IOTEST programme you can establish the values for when the servo is at start, middle and end positions. The SIOC script programme can then send any value within these limits and the servo will move to that position.

It is possible on some servos to adapt them so that they can rotate 360deg, however, to achieve this you need to disconnect the drive to an internal potentiometer, thereby losing reference points and creating the problem that you mentioned. It is possible to keep some degree of control by counting within the SIOC programme, but it is messy as you need a switch to create a start point and if you turn off the computer before you remove power to the servo, it goes wild - overall not to be recommended.

Hondacop

Re a FSUIPC offset - I did not see one when I last looked. Consequently, I was going to use an analogue input from the brake pedal travel to create a value to drive the pressure gauge. The idea of also linking in the parking brake was a good one Geremy.

Regards

David

[HondaCop]

I was going to use an analogue input from the brake pedal travel to create a value to drive the pressure gauge.

Hmmmm You have a good point here, David. I know this might just be coincidence but in the autobrake panel, there are 4 "steps" for braking.

1
2
3
Max

When you look at the brake pressure gauge, the gauge is numbered from 0 to 4. In other words, once can deduce the following relationship between the Autobrake panel and brake pressure gauge:

1 on Autobrake panel = 1 on brake pressure gauge
2 on Autobrake panel = 2 on brake pressure gauge
3 on Autobrake panel = 3 on brake pressure gauge
Max on Autobrake panel = 4 on brake pressure gauge

So yes, maybe using the toe brake travel where max toe brake equals 4 on the brake pressure, could do the trick!

[ian@737ng.co.uk]

mornin' chaps........
first the brake pressure gauge shows the hydraulic pressure available in the accumulator (reservoir). normal operating pressure is 3000lbs/sq. in. here's a quote from the POH.....

"Brake Accumulator
The brake accumulator is pressurized by hydraulic system B. If both normal and
alternate brake system pressure is lost, trapped hydraulic pressure in the brake
accumulator can still provide several braking applications or parking brake
application."

the 1-2-3-MAX settings on the autobrake are different levels of controlled deceleration
which the autobrakes apply on application.

david, quite correct, there is no offset i can see for the brake pressure. however remembering that the pressure is generated by the pumps, it may be an idea to use the engine hydraulic pressure offsets of (Eng1) 08D8 and (Eng2) 0970. i've checked these this morning and both are returning a value of around the 3200lbs.

hope that helps you out.

have a great day chaps ..... ian

[HondaCop]

david, quite correct, there is no offset i can see for the brake pressure. however remembering that the pressure is generated by the pumps, it may be an idea to use the engine hydraulic pressure offsets of (Eng1) 08D8 and (Eng2) 0970. i've checked these this morning and both are returning a value of around the 3200lbs.

Ian, you are the man!!! I guess we can use those offsets indeed. :D

[Jackpilot]

Read this, might interest you

http://www.mycockpit.org/forums/showthread.php?t=13213&highlight=real+gauge

No code, real gauge, works very well.
full specs :

http://www.mycockpit.org/forums/attachment.php?attachmentid=975&d=1219119026

video on the last page of the thread.

[fordgt40]

Jack

Thanks, a very interesting thread - should use the search function more often!

Sadly, I have already built my servo gauge, however, that thread will be useful in the future

Regards

David