ehonda

thanks for the info guys, I tried the priority and task reduction ideas with no success, I'm going to try and get a demo of the labview RT module and see how that works. e

Hello all, I am creating a simulator using WinXp Pro and Labview 8.0 which communicates to a device serially using RS-485. The serial bus is at 115.2kbaud. The device sends a command to the simulator in a polling fashion, where the command is sent every ~2msec. The device does not wait for any acknowledgement or response, and will send another cmd in the next ~2ms... over and over. I need to send a complete response to the command before the device sends it's next command (the 2ms window). Using an oscilloscope and the application I wrote (set VISA comm--->while loop with serial read then write, no delays) I have noticed that it takes anywhere from 1 to 2.7ms(always varies) for my simulator computer port to write to the data bus. If it takes longer than 2ms to write, the data overlaps and the device craps out. I am pretty sure the problem is not labview and that its a windows to port issue. Does anyone know how I can reduce the winXP delay to the serial port? note: I have observed that when I first start my Labview application it transmits very fast ~700uS, but after ~ 2secs it slows down to 2.7mS any input would be much appreciated thx e