Touchcal Technology
The Q478 utilizes Action Instruments’ TouchCAL technology which greatly simplifies configuration. To set the input frequency range, the user pushes the CAL button to enter the calibration mode. The high input frequency is applied first, while the INPUT LED is lit, and the CAL button is pushed to store the value. The low input frequency is then applied and pushing the CAL button again stores the low frequency input.

The high and low input ranges are stored in non-volatile memory and correspond to the high and low output range which is selected via DIP switches.

To precisely adjust the output, the user adjusts the input frequency while the OUT LED is lit until the desired output level is achieved. The output levels are locked-in by pushing the CAL button. Diagnostic LEDs show the operation mode of the device.

Diagnostic LEDs
The Q478 utilizes three diagnostic LEDs. One is the dual fuction LED signal monitor. This green LED indicates DC power and input signal status. Active DC power is indicated by an illuminated LED. If the input signal is 10% more than full scale range, the LED will flash at 8Hz. Below 0% the flash is 4Hz.

The yellow IN LED, when on, denotes input programming modes. The red OUT LED, when on, denotes output programming modes (see Configuration, Calibration and Figure 1 for details).

Configuration
A major advantage of the Q478 is its wide ranging capabilities and ease of configuration. The Q478 enables virtually 99% zero and span adjustability. Any 2Hz range from 0 to 10,000Hz can be converted to a full scale output signal (e.g. 0-2Hz/4-20mA or 9998- 10,000Hz/4-20mA).

Unless otherwise specified, the factory presets the Model Q478 as follows:

For other I/O ranges, refer to Table 1 for output range (SW2, 1 through 8) switch settings and to Table 2 for sensitivity switch setting (SW2, 9 & 10). For quick and easy calibration mode reference, see the step-bystep flow chart in Figure 1.

1. With power off, snap off the face plate by lifting the right edge, away from the heatsink. Then, slide heatsink forward and off the module. Note, the output switch block (SW2) is located under the heat sink. Choose the desired output voltage/current range from Table 1 and set positions 1-8 of SW2.
2. Set the input sensitivity switch (SW2, 9 & 10) to LO for input amplitudes between 150mVp and 50Vrms, with noise rejection to 1Vp or, to HI for input amplitudes between 500mVp and 150Vrms, with noise rejection up to 10Vp.

Calibration
For best results, calibration should be performed in the operating installation, allowing at least one hour of thermal stability of the system. If pre-calibration on a test bench is preferred then an output load equal to the input impedance of the device(s) connected to the Q478 output is recommended, along with a 1 hour warm up period.

1. Install the module on a piece of DIN rail and the I/QRail mounting combination. See the I/ QRail data sheet for details.
2. Connect the input to a calibrated frequency source and the output to a voltage or current meter. Apply power and allow the system to reach thermal equilibrium (approx 1hour).
3. Adjust the input frequency to the desired maximum and observe that the ouput has increased and is sensing the input. If this is not observed, turn the sensitivity potentiometer in a counterclockwise direction until the output changes proportionally to the input.
4. With the green LED on press the CAL button for 5 sec. to enter the calibration mode. The yellow and green LEDs should now be on.
5. Input the maximum desired frequency (if not done already) and press the CAL button to store. The yellow LED should now be the only LED on.
6. Input the minimum desired frequency and press the CAL button to store. The green and red LEDs should now be on.
7. To precisely adjust the maximum output, adjust the input frequency until the output reads within +0.1% of the maximum selected output range. This typically occurs near 90% of the HI input frequency. Press the CAL button to store the value. The red LED will now be on.
8. To precisely adjust the minimum output, lower the input frequency until the output reads within +0.1% of the minimum selected output. This typically occurs near 10% of the HI input frequency. Press the CAL button to store the value. The yellow and Red LEDs should be on. The green LED should be dim.
9. Press the CAL button one final time to exit the calibration mode. The green LED should now be on.
10. Check the minimum and maximum input-tooutput calibration. Repeat steps 1 through 8 if calibration is not within desired specifications.