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4200 Transmitters
September 2022
Transmitter Circuit Zero and Span Adjustment
WARNING
On an intrinsically safe instrument, the current monitoring across TP1 and TP2 during operation must be with an approved
meter. Personal injury or property damage may result from fire or explosion if an approved meter is not used in a
hazardous area.
Calibration of the transmitter consists of adjusting the zero and span for a 1 to 5 volt DC output across a 250 ohm
resistor, or a 4 to 20 mA output current for a specific travel. If necessary refer to the type number on the nameplate to
determine the configuration of the transmitter.
1. Remove power from the instrument.
2. Connect the transmitter as shown in figure 8.
3. Remove the transmitter covers. Note that you will need to loosen the set screws (key 106) before removing the
covers.
4. Stroke the valve or device to the mid‐stroke position
5. Check the potentiometer alignment by connecting a digital voltmeter (DVM) as follows:
a. For all transmitters (except a 4212 or 4222) connect between TP3 (+) and TP4 (-) on the printed wiring board.
b. For a 4212 or 4222 transmitter, connect the DVM between TP5 (+) and TP6 (-).
6. Apply power to the instrument.
7. The DVM should read 1.25 ±0.05 volts DC. If not, perform the potentiometer alignment procedures in the
Installation section.
8. Stroke the valve or device to the point of travel where the transmitter output is to be 4 milliamperes DC.
9. Adjust the zero potentiometer (R1, figure 5) until the output is 4 milliamperes DC (1.00 volt across 250 ohms).
10. Stroke the valve or device to the point of travel where the transmitter output is to be 20 milliamperes DC.
11. Adjust the span potentiometer (R2, figure 5) until the output is 20 milliamperes DC (5.00 volts across 250 ohms).
12. Some small interaction between the two adjustments may occur. Repeat steps 8 through 11 until the error is within
the application requirements.
13. For a 4211 or 4221 transmitter without position switches, calibration is complete. Refer to the installation and/or
operating information to place the transmitter in service.
14. If calibration is complete, replace the transmitter covers. Be sure to tighten the set screws (key 106) securely after
installing the covers. For transmitters with position switches, refer to the high and low position switch adjustment
procedure below.
High and Low Position Switch Adjustment
Note
The "high" and "low" designations refer to the voltage output of the position potentiometer. See figure 7 for relationship to valve
or actuator travel.
The high position switch must be adjusted before the low position switch. If the deadband of either the high or low position
switches exceeds the difference between the set points of the high and low position switches, both position switches may be on at
the same time.
20
Instruction Manual
D200354X012
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