4~20mA Outputs Notes

Range of Output 1
· Field selectable from the following:
Output Selection		Range
Linear oxygen		0 – 0.1% oxygen to 0 – 100.0% oxygen 0 – 1000ppm oxygen to 0 – 1,000,000ppm oxygen
Low Range Linear oxygen		0 – 0.001% oxygen to 0 – 1.0% oxygen 0 – 10ppm oxygen to 0 – 10,000ppm oxygen
Range of Output 2
· Field selectable from the following:
Output Selection	Zero Range		Span Range
Carbon Dioxide	0 – 90%		10 – 100%	Min span 10%
Reducing Oxygen	10-1 – 10-10 %		10-1 – 10-30 %	Min span three decades
	In one decade steps.
Oxygen sensor EMF	0 – 1100mV		1000 – 1300mV
	In 100mV steps		In 100mV steps
Sample Oxygen	0 – 0.1%		0.01 – 20%	Min Span 0.01%
	0 – 1000ppm		100 – 20,000ppm	Min span 100 ppm
Low oxygen	0 – 99.9%		0.1 – 100% oxygen	Min span 0.1%
	0 - 999,000ppm		1,000 - 1,000,000ppm	Min span 1,000ppm
Logarithmic Oxygen	0.1% O2		Fixed 20% O2 Fixed

4.6 4 - 20 / 0 - 20mA OUTPUTS

There are two analog output channels.

The output function and range can be selected for both channels. See set-up 25 to 30.

NOTE: If oxygen is selected to be transmitted on either channel, the output current will be driven to 20mA while the sensor

heats up to over 650°C.

NOTE: If “Not Used” is selected for channel 1 output, menu items that relate to both output channels will be hidden.

 

14. OUTPUT CHANNEL #1, 0 - 20mA or 4 - 20mA

The output channel can be scaled 0 to 20mA or 4 to 20mA to represent the parameter that is selected in set-up function

25.

Options:

1. Not Used *

2. 4 - 20mA

3. 0 - 20mA

15. OUTPUT CHANNEL #2, 0 - 20mA or 4 - 20mA §

The output channel can be scaled 0 to 20mA or 4 to 20mA to represent the parameter that is selected in set-up function

28.

Options:

1. 4 - 20mA *

2. 0 - 20mA

16. 4 to 20mA CALIBRATION OPTIONS, CHANNEL #1 §

Select the calibration method for the 4 - 20mA output channel #1.

The output channels can be either calibrated by simply pressing the ‘AUTO CAL’ button, or can be trimmed at both the

4mA and 20mA ends of the scale using an external multimeter.

Options:

1. Auto Calibration *
2. Manual Calibration
3. Set 4mA Trim
4. Set 20mA Trim

If ‘AUTO CAL’ is selected, the output channel is calibrated when ‘Auto Cal’ is initiated from the keyboard (See section

6.3).

If ‘MAN CAL’ is selected, it is necessary to trim both ends of the 4-20mA output range using the 4mA and 20mA

options in this menu item. Selecting ‘MAN CAL’ inhibits the ‘Auto Cal’ process of this channel.

Always do the 4mA trim first, and then the 20mA trim. After trimming both ends of the scale, return the

‘CALIBRATION OPTIONS’ menu option back to ‘MAN CAL’ (not ‘AUTO CAL’), or the calibration factors will be over written by the next ‘AUTO CAL’.

For more details on calibrating the output channels, see section 6.3.

NOTE: The analyser will only stay in either ‘4mA TRIM’ or ‘20mA TRIM’ modes for 30 minutes before it

automatically returns to ‘MANCAL’.

17. CALIBRATE 4mA, CHANNEL #1 §

This menu item only appears if ‘Set 4mA Trim’ is selected in Set-up 16.

Range: 0 to 25mA, Default is 4.00mA

For full details on the calibration of the 4 - 20mA output channels, see section 6.3.

18. CALIBRATE 20mA, CHANNEL #1 §

This menu item only appears if ‘Set 20mA Trim’ is selected in Set-up 16.

Range: 0 to 25mA, Default is 20.00mA

19. 4 to 20mA CALIBRATION OPTIONS, CHANNEL #2 §

Select the calibration method for the 4 - 20mA output channel #1.

For more details, see Set-up 16 and section 4.5.

Options:

1. Auto Calibration *
2. Manual Calibration
3. Set 4mA Trim
4. Set 20mA Trim

20. CALIBRATE 4mA, CHANNEL #2 §

This menu item only appears if ‘Set 4mA Trim’ is selected in Set-up 19.

Range: 0 to 25mA, Default is 4.00mA

For full details on the calibration of the 4-20mA output channels, see section 6.3.

21. CALIBRATE 20mA, CHANNEL #2 §

This menu item only appears if ‘Set 20mA Trim’ is selected in Set-up 19.

Range: 0 to 25mA, Default is 20.00mA

 

6.3 D/A (4 - 20mA output channels) Calibration

The calibration can either be done using the ‘Auto Cal’ or ‘Manual Cal’.

Auto Cal

The ‘Auto Cal’ mode is selected in set-up 16 (and 19 for channel 2).

The analyser will automatically divert the output back to the input, measure the offset and span, and record the calibration factors for each channel.

If either of the channels are selected to be calibrated manually, the factors will not be changed by an ‘Auto Cal’.  Manual Cal

The ‘Manual Cal’ mode is selected in set-up 16 (and 19).

Set the 4mA calibration first and then the 20mA calibration.

1. Select ‘Set 4mA Trim’ in set-up 16 (or 19).
2. Return to RUN mode.
3. Measure the output on the channel to be calibrated with a digital multimeter. If the current is not exactly 4.00mA, return to set-up mode and change the 4mA calibration factor in set-up 17 (or 20).
4. Re-measure the current while back in RUN mode until the current is within 3.9 to 4.1mA.
5. Return to set-up mode and select ‘Manual Cal’ in set-up 16 (or 19).

Set the 20mA calibration factor.

1. Select ‘Set 20mA Trim’ in set-up 16 (or 19).
2. Return to RUN mode.
3. Measure the output on the channel to be calibrated with a digital multimeter. If the current is not exactly 20.00mA, return to set-up mode and change the 20mA calibration factor in set-up 18 (or 21).
4. Re-measure the current while back in RUN mode until the current is within 19.9 to 20.1mA.
5. Return to set-up mode and select ‘Manual Cal’ in set-up 16 (or 19).

 

This calibration is now saved in battery backed memory until

• The factors are changed in the manual calibration
• The analyser is forced into a COLD-START (see section 6.1)
• The calibration mode in set-up 16 (or 19) is changed to Auto Cal and an Auto Cal is initiated.

NOTE: The 4mA or the 20mA trim mode will only be held on the output channels for 30 minutes before automatically returning to ‘Manual Cal’ mode in set-up 16 (or 19).

Open the case by removing the two screws either side of the display. The connector for the analogue output can now be seen.