Thanks for the help from everyone over the last couple of weeks, my first prototype picaxe powered flight simulator instruments operated last night 
Two servos driven by an 18X operate the artificial horizon, and a stepper motor driven by an 08M operates the heading indicator. (The flight simulator is Microsoft's FS2004) Both picaxe's are connected to the same serial port, but they only receive, then send when prompted, so there's no collision problems.
What I have done is every 50ms the PC sends the data to both Picaxe's. If the picaxe is at a SERIN and receives the data then it responds with an "OK" and the PC updates it's record to show that the picaxe has been updated. If the Picaxe hasn't finished moving from the last update, then the PC gets no "OK" and it doesn't flag the picaxe as updated.
The instruments are butt-ugly at the moment - paper disks on a balsa frame - but they work. Once I get proper ones made I'll post a short video.
Richard
Two servos driven by an 18X operate the artificial horizon, and a stepper motor driven by an 08M operates the heading indicator. (The flight simulator is Microsoft's FS2004) Both picaxe's are connected to the same serial port, but they only receive, then send when prompted, so there's no collision problems.
What I have done is every 50ms the PC sends the data to both Picaxe's. If the picaxe is at a SERIN and receives the data then it responds with an "OK" and the PC updates it's record to show that the picaxe has been updated. If the Picaxe hasn't finished moving from the last update, then the PC gets no "OK" and it doesn't flag the picaxe as updated.
The instruments are butt-ugly at the moment - paper disks on a balsa frame - but they work. Once I get proper ones made I'll post a short video.
Richard