PMDG 737 Altitude setting above 32700 gives negative value.

[bill1798]

Hello all,

Apologies in advance if this is an old question, I've had a good hunt around and haven't come across the question or the solution.

I am a newby at putting together external flightsim controls and have some switches, LED's and Encoders set up on a breadboard.  Using FSUIPC4 with Mobiflight V7.7.0. I have had a lot of success using inputs and outputs into a PMDG B737 running on MS FSX.  The problems have come with  7 segment LED Displays.  I have set up a display to show the altitude setting on the MCP.  This works fine until I try to set an altitude above 32700 at which point instead of displaying 32800 I get -32736, if I continue to rotate the encoder clockwise the value reduces in steps of -100 so always retaining the 32 at the end of the value.

This value appears to be coming in from FSUIPC as the Output tab in MobiFlight has 2 columns showing the FSUIPC Value and the Output Value, both of which show -32736.  I am using offset 652E with an Int value type and a Byte size of 2.  I know from my forays into programming that a Signed Int value has a range of -32768 to 32767 and with a value of 32,768 bit 15 is 1 and so as this is a signed Int value all values after this point will be negative, maybe the signed Int is the issue.  I'm guessing that this isn't a new issue and that that there is probably a setting in an ini file some where to resolve it, so apologies again if this is a simple setting that I have missed but with little experience I have run out  of ideas.

As said above I'm Using FSUIPC4 with Mobiflight V7.7.0, PMDG B737NGX in FSX, with all patches and updates applied.

I appreciate any assistance.

Regards

 

Bill.

[Pete Dowson]

2 hours ago, bill1798 said:

I have set up a display to show the altitude setting on the MCP.  This works fine until I try to set an altitude above 32700 at which point instead of displaying 32800 I get -32736,

You need to treat it as unsigned int, not int, though an int is usually 4 bytes (32 bits). You should declare it as an unsigned short, or whatever your software understands. I know 16-bit values as WORD (Windows programming definition0.

2 hours ago, bill1798 said:

This value appears to be coming in from FSUIPC as the Output tab in MobiFlight has 2 columns showing the FSUIPC Value and the Output Value, both of which show -32736.  I am using offset 652E with an Int value type and a Byte size of 2.

An unsigned short int has a range of 0 to 65535.

Pete