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This post was last edited by xlh15979 on 2017-5-12 at 13:30 1

It depends on the type of transmitter that the poster is using; if it’s a smart transmitter, it can be adjusted using a handheld controller or the built-in display. For analog transmitters, adjustment is done by tweaking the zero-setting potentiometer. It is not recommended to attempt such adjustments without a standard temperature source or resistance box. It is recommended to ask the manufacturer of the product about the specific adjustment method.

There are numerous manufacturers and models of temperature transmitters; the original poster should at least provide detailed information about the device so that others can offer advice.

The temperature transmitter can be adjusted, but communication equipment is required; it varies from manufacturer to manufacturer. It’s best to contact your supplier and send it to them for modification

The Pt100 platinum resistance temperature transmitters produced by Yunnan Yunrun Instrument Manufacturing Co., Ltd. usually offer six standard range options for selection. Special measurement ranges can be provided upon customer request. Users can also adjust the range of the Pt100 platinum resistance transmitter manually using calibration instruments such as standard resistance boxes and digital ammeters. By changing the wiring of the solder joints on the circuit board and conducting re-calibration, the range of the transmitter can be adjusted so that its measurement range meets the requirements of the application site. Due to the inherent characteristics of platinum resistance temperature transmitters, changes in the range will affect the calibration points for 4 and 20 mA. If the transmitter’s calculations are based on the true zero point (the temperature at which the theoretical output current is zero), then calibrating the transmitter is very simple: calculate the SPAN range and the temperature value of the true zero point according to the desired range, then determine which row in the temperature range table (Table 1) and the true zero point table (Table 2) corresponds to this temperature value; short-circuit the appropriate solder joints as indicated in the tables, and adjust the transmitter to the desired range following the calibration steps. 1. Prepare a resistance box (with accuracy of ±0.01 ohms), a four-and-a-half-digit digital ammeter (with an accuracy of 0.05% within the 0–20mA range), and a DC 24V power supply. 2. Determine the required range: TH is the upper limit of the range (the temperature value when 20mA is output), and Tlo is the lower limit of the range (the temperature value when 4mA is output). 3. Calculate the SPAN range: SPAN range = Upper limit – Lower limit = TH – Tlo. 4. Calculate the true zero point: True zero point = Lower limit – (SPAN range / 4) = Tlo – (SPAN range / 4). 5. Visit http://www.yunrun.com.cn/Product/115.html and look up in the table the temperature values corresponding to the calculated SPAN range and true zero point; pay attention to the solder joints that need to be shorted. 6. Open the bottom cover of the housing, use solder wire to short-circuit the solder joints that need to be connected on the circuit board, and remove the previously soldered joints to ensure they remain in an open circuit state. 7. Change to Pt100. 6. Open the bottom cover of the housing, use solder wire to create short circuits at the solder joints that need to be shorted on the circuit board, and remove the previously soldered joints to ensure they remain in an open circuit state. The equivalent resistance value of the Pt100 platinum resistor corresponding to a 4mA output from the transmitter; adjust the Z (zero potentiometer) so that the output is 4mA ± 0.01mA. 8. Enter the equivalent resistance value of the Pt100 platinum resistor corresponding to a 20mA output from the Pt100 transmitter, and adjust S (the zero potentiometer) so that the output is 20mA ± 0.01mA. 9. Repeat Step 7 and Step 8 until both the transmitter zero point and range are calibrated. Note: Range and zero adjustment affect each other, so repeated adjustments are necessary. 10. Turn off the power and remove the wiring. 11. Redesign of the labels for Pt100 platinum resistance temperature transmitters. Temperature transmitters: http://www.yunrun.com.cn/Product/115.html. Thermocouple temperature transmitters: http://www.yunrun.com.cn/Product/371.html. Thermal resistance temperature transmitters: http://www.yunrun.com.cn/Product/372.html

The range is the difference between the upper and lower limits of measurement. Adjustments can only be made to these upper and lower limits. If the lower limit is to be set to -20°C, first send the standard resistance value corresponding to -20°C to the temperature transmitter; at this point the transmitter will output 4mA. No, instead adjust the zero potentiometer so that 4mA is obtained. Then input the standard resistance value corresponding to the upper temperature limit – at this point the transmitter will output 20mA. If that’s not correct, adjust the range potentiometer. Repeat this process 2-3 times until the desired setting is achieved.

1. Check whether the upper and lower limits of the transmitter you are using meet your requirements； 2. If a smart transmitter is to be configured using a dedicated handheld device ； 3. For ordinary transmitters, a resistance box is used to set the standard resistance values for the upper and lower limits, after which adjustments are made ；

We need to let everyone know the specifications and model of the instrument, as well as whether it can communicate. Otherwise, there’s only the option of asking the manufacturer

The range is adjustable; the specific details need to be provided by the supplier. For -20 degrees Celsius, anti-freezing measures need to be considered.

I don’t know which manufacturer and model you are using for on-site temperature control; at least MTL does not limit the range to a fixed value that cannot be changed.