4. ANALOG OUTPUT RANGE CONFIGURATION
Refer to the Drawing of Ruby-MM-1612 on Page 8 for locations of headers described in Sections 3 and 4. Refer to Figure 4.1 on Page for an explanation of the voltage reference circuitry. Also refer to Table 4.1 for a quick guide to output range configuration and jumper settings.
Header J4 is used to configure the analog outputs. Four items are configurable: (1) On-board reference full-scale voltage, (2) D/A full-scale voltage, (3) unipolar / bipolar select, and (4) adjustable reference voltage. Items 2 and 3 in turn are configured separately for each bank of 8 analog output channels.
On-Board Reference Full-Scale Voltage Selection
An on-board reference voltage generator provides a +5.000V full-scale voltage output. This voltage is used as the basis for all on-board full-scale output ranges. This +5 reference drives an operational amplifier, from which the fixed references are derived. The gain of this amplifier is normally set to 1, so that its output is also +5.000V. However, you can change the gain to 2 so that the output is +10.00V. For an output of +5V, install a jumper in location 5 in header J4. For an output of +10V, remove the jumper from this location. The output of this amplifier is used to generate the full-scale voltages for both bipolar and unipolar output ranges.
D/A Full-Scale Voltage
The full-scale voltage defines the full output range capability of the analog outputs. Locations F A on header J4 are used to select the full-scale voltage. Each bank of eight channels has its own selection pins for full-scale voltage. Thus each bank of eight channels may be configured differently. Install only one jumper in these locations for each bank of channels. Position F is for the Full-scale voltage (5V or 10V depending on the jumper in position 2, explained above). This is the default setting. Position A is for the Adjustable reference voltage (see section 4.4).
Unipolar / Bipolar Output Range
Unipolar output ranges are positive voltages only (for example 0 - 5V), while bipolar output ranges include both positive and negative voltages (for example ±5V). To select unipolar outputs, install a jumper in position U on J4. to select bipolar outputs, install a jumper in position B. Install only one jumper in these locations for each bank of channels.
Adjustable Reference Voltage
One full-scale voltage range is adjustable by the user. It is preset to 2.5V (for both 0-2.5V and ±2.5V ranges), but may be set anywhere between 0V and 2.5V. To adjust this voltage, apply a voltmeter to the top pin of header J4 underneath either A mark and turn the screw on potentiometer R4 (the fourth from the left / second from the right in the row of blue potentiometers at the top of the board) until the voltmeter reads the desired voltage.