Omega Engineering CIO-DAC08, CIO-DAC16 user manual Signal Connection

3.9 Signal Connection

The analog outputs of the CIO-DAC## are two-wire hookups. A signal, labeled D/A # OUT on the connector diagram below, and a Low Level Ground (LLGND). The low level ground is an analog ground and is the ground reference which should be used for all analog hookups.

Possible analog output ranges are:

Bipolar Ranges	+10V	+5V	+2.5V
	and
Unipolar Ranges	0 to 10V	0 to 5V	0 to 2.5V

See the range select switch in section 3.5.

Each of the DAC## outputs are individually buffered through an OP07 operational amplifier (OP-AMP). The OP07s are socketted so that if one fails it can be replaced in the field. The OP07 for each channel is located just below the calibration potentiometers for that channel.

At the full rated output swing of ±10V, each channel is capable of sinking or sourcing ±5 mA. That means a load of 2K Ohms can be connected to each channel.

As the load resistance is raised from 2K up to 10 Megaohms or more, the output load on the DAC decreases. Any load resistance greater than 2K is fine.

As the load resistance decreases, the output load increases. The OP07 responds by producing a lower output voltage. If your CIO-DAC## will not produce the output voltage specified by the code & range combination, it is a good idea to check the load with an ohm meter.

Under normal circumstances you will not damage the OP07 by connecting the output to ground. If your connection results in a failure of the OP07, chances are good that there was some potential at the connecting point in addition to a load at ground or between 0 and 2K ohms. Explore the point with a DVM before reconnecting the CIO-DAC## (and after replacing the OP07 of course). Connect the negative lead of the DVM to any LLGND pin of the CIO-DAC##.

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