Remote Processing RPC-210 - Manual (Page 47)

ANALOG I/O BASIC SECTION 10
Page 10-5
Figure 10-2 5V A nalog IO calibration
you should use the 2.5V range instead.
To calibrate or otherwise adjust the reference, connect
volt meter ground a t J10-2. Connec t voltmeter (+ ) to
W11, pin 1, side closer to end of card. Adjust R16 for
5.000 volts or other desired voltage.
Make sure jum per W11 is installed.
2.500V Reference
J um p er W 1 1 m u st be r em o ve d . W he n re m ov e d, A / D
and D/A ranges are 0 - 2.5V.
There is no adjustment for this reference. The voltage,
measured at W11, pin 2, nor mally is 2.50 V but can
r a n ge f ro m 2 . 45 to 2 . 55 V D C .
ANALOG OUTPUT
Two analog outputs are available at J10, pins 17 and 19.
Output voltage range depends upon the setting of jumper
W11. When W 11 is installed, output ran ge is about 0 to
5 volts. Removed, range is about 0 to 2.5 volts. There
is a small am ount of offset at the 0 volt output.
Output Command
The A OT co mma nd is used to set an a nalog output.
AOT channel, value
channel specifies the an alog channe l to write to a nd is
either a 0 or 1. Channel 0 is at J10-17, channel 1 is at
J10-19.
value is a number from 0 to 4095. The higher the
numbe r, the mor e positive the outp ut.
The follow ing exam ples conver t a voltage to a num ber to
produc e an output.
AOT C,819 * V 0-5V range
AOT C,1638 * V 0-2.5V range
A 1 bit, or count, change in value produces a 0.001221
volt change in the 0-5V range and changes 0.00061035
volts in the 0-2.5V range.
Maximum current output should be limited to 1 mA. for
each chan nel.
ANALOG POWER SUPPLY OUTPUT
Some power is available at J10 for external analog
amplifiers, buffers, and sensors. J10-18 provides about
+ 8V and J10-20 is about -8V.
The amount of current available depends upon several
factors. T his power is generated from the RS-232
conver ter chip U 12. If there is a lot o f transm it activity
on both serial ports current is reduced. T he amount
depends upon load imp edance. Analog outputs (D/ A’s)
can also use power if they are driving a load. W hen the
analog I/O range is 5V m ore current is consumed.