I am currently trying to convert synchro output signals to analog signals +/-10V for use as feedback into the PCI-7344 Motion controller card.

[motionman]

I currently am converting the synchro signals to 16bit digital. The problem is converting the binary into analog using DAC's so that .............. 0000|0000|0000|0000 (which is physically 0 degrees) will output 0 volts out of the DAC. Every DAC that I research sees 1000|0000|0000|0000 as 0 volts. I think there might be a way to map the digital output of the S to D converter to the digital input lines as feedback - but I have no idea how to accomplish this. Any help would be greatly appreciated!!!

[Andy_Bell]

Motionman,

Could you give me more information on the synchro signals you are trying to convert? Do you want to use one of the output lines on the PCI-7344 as your input for your analog feedback? What is your application? Thanks for the additional information.

Regards,
Andy Bell
Application Engineer
National Instruments

[AA Dan]

I found two references to the 'Scott "T"' circuit being used for synchro-to-digital conversion in a closed loop feedback type II setup:
http://www.evaluationengineering.com/pctest/articles/0399daq.htm
figure 3.

and
"The Measurement, Instrumentation, and Sensors Handbook" by John G. Webster, CRC Press & IEEE Press. I'd imagine from your question that you are familiar with this kind of circuitry. These figures include some hardware solutions, but are fairly vague about the actual DACs being used.

If you are using a National Instruments DIO DAQ to measure the output of the Scott "T" circuit, then you are correct, and you could easily create a table that maps various digital input patters to various output voltages. The National Instruments technical support g
roup should be able to describe in further detail how to do this in software. www.ni.com/ask