HELP! We are 8 years into a 12-year study, and our original computers are failing. There is a serious possibility that the study will not be completed, because we cannot find computers which are compatible with our equipment and which can do the job.
We need to be able to measure and control scientific processes with millisecond accuracy. We can find nothing available which can do our task. Specifically we need to be able to do the following:
1. Collect real world analog data from 8 signal lines once every millisecond, over a period of 4 seconds.
2. Calculate a value from those data, and determine whether or not it exceeds a value determined at the beginning of the experiment.
3. Output the boolean result of the comparison to a digital port before the next millisecond ends.
4. When selected numbers of milliseconds have passed, output certain boolean signals to the digital port to operate equipment during different stages of the experiment.
5. After the 4 seconds are over, save the collected data to disk.
We were able to do this under MS-DOS. But now we are not able to find a machine capable of handling this task. Every computer we have tried messes up on the timing.
- We tried a specialized computer running Unix and C+. If someone who was watching hadn't intervened, the equipment might have been destroyed. It changed the order of the experiment, collecting all of the data first, and saving it to disk. THEN it did the calculations and output the boolean variable from the comparison. Last, it output the experiment stage variables. Somehow, the operating system did not seem to understand that the timing of all of these operations was important, and it rearranged them to process the data faster.
- Windows lets us do I/O only once every 55 millisecionds.
- We have similar problems in Mac OS.
- We have a little board level computer which can do this, which is currently on the market. It has a serial port so a computer can be its console. But it can't communicate with Windows. You have to have a DOS computer to use it.
- We tried e-prime, but it has too much latency, with the output coming several millisecinds after the input, and sometimes the output is bunched up.
I originally posted this in the Quickbasic forum, and they said to try here.