External Voltage Input to DrDaq

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External Voltage Input to DrDaq

Post by mbelding » Wed Jul 12, 2006 5:55 am

I'm trying to monitor an external voltage with the external input (telephone jack) of my DrDaq. The voltage (+) side goes to pin1, and (-) ground goes to pin2. Pin3 and Pin4 are no connects for me. When I turn on the input channel in PicoLog, all it shows me is '******' for the read value. How do I configure the input for just plain voltage readings, no scaling.

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Post by Michael » Wed Jul 12, 2006 9:01 am


YOu will have to refer to the manaul on this one.

The EXT inputs for the DrDAQ use a resistor to sense the input range. YOu will have to create a DrDAQ DDS file as mentioned in the manual.

Here is the basic outline:
External Inputs
Each external input socket has four connections:

Pin Function
1 Input channel with 100k pull-up to 2V5
2 Ground
3 Sensor type detect with 100k pull-up to 2V5
4 Power approx 2mA at 3-5V

The DrDAQ driver has built-in scaling for each of the built-in and Pico-supplied sensors. You can incorporate scaling for your own sensors by adding a file called drdaq.dds, which contains details of your sensor.

For external sensors, this resistor should be fitted in the sensor. Customers should use one of the following resistors: 1k0, 2k2, 3k3, 5k6, 7k5 and 10k. The resistor used should be 1% tolerance or better.

The following resistor values are reserved and must not be used: 330k, 220k, 180k, 150k, 120k, 110k, 100k, 91k, 82k, 75k, 68K.

For internal sensors, the following 'virtual' resistor values should be used:

1 Sound Waveform 1200
2 Sound Level 1300
3 Voltage 1500
4 Resistance 1600
5 pH 1400
6 Temperature 1100
7 Light 1000

I hope this helps.

Michael - Tech Support
Pico Technology
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