Emerson ROC364 Manual de instrucciones descargar pdf (Pagina 57)

ROC364 Instruction Manual

3-23 Input and Output Modules Rev Jun/05

3.5.2.1 Check AO Current Loop Source Installations

Equipment Required: Multimeter

Personal Computer running ROCLINK configuration software

1. Taking appropriate precautions, disconnect the field wiring going to the AO module

terminations.

2. Connect a multimeter between the B and C terminals of the module and set the multimeter to

measure current in milliamps.

3. Using ROCLINK configuration software, put the AO point associated with the module under test

in Manual mode (Scanning Disabled).

4. Set the output to the High Reading EU value.

5. Verify a 20-milliamps reading on the multimeter.

6. Calibrate the Analog Output High Reading EU value by increasing or decreasing the “Adjusted

D/A 100%” value.

7. Set the output to the Low Reading EU value.

8. Verify a 4-milliamps reading on the multimeter.

9. Calibrate the Analog Output Low Reading EU value by increasing or decreasing the “Adjusted

D/A 0%” value.

10. Enable scanning (Scanning Enabled or Auto) for the AO point, remove the test equipment, and

reconnect the field device.

11. If possible, verify the correct operation of the AO module by setting the High Reading EU and

Low Reading EU values as before (Scanning Disabled) and observing the field device.

3.5.2.2 Check AO Voltage Source Installations

Equipment Required: Multimeter

Personal Computer running ROCLINK configuration software

To check operation of the Analog Output module powering a voltage device:

1. If the resistance value (R) of the field device is known, measure the voltage drop (V)

across the device and calculate the output EU value using the following formula.

EU value = [((1000V/R – 4) ÷ 16) × Span] + Low Reading EU,

where Span = High Reading EU – Low Reading EU

2. Compare the computed value to the output EU value measured by the ROC with ROCLINK

configuration software. It is normal for the reading to be several percent off, depending on the

accuracy tolerance of the device and how rapidly changes occur in the output value.

3. Calibrate the Analog Output EU values by increasing or decreasing the “Adjusted D/A % Units.”

4. If the Analog Output is unable to drive the field device to the 100% value, confirm the +V

(1 to 5 volts) voltage is present at the field device.

♦ If the voltage is present and the device is not at the 100% position, the resistance value of the

device is too large for the +V voltage. Use a field device with a lower internal resistance.

♦ If the voltage is not present at the field device, but it is present at field wiring terminal B,

there is excessive resistance or a break in the field wiring.

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Emerson ROC364 Manual de instrucciones Pagina 57