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Transmitter Function

Transmitter Function

Select products that include a Transmitter function.

  • TOC
    • Top
    • Transmitter
    • Transmitter Function
    • Calibration, Offset and Span
    • Footer

Find Transmitter select ⇒ Input ⇒ Output

  • 4-20mA
    • 4-20mA, Select Output
    • 4-20mA 2-Wire
      • 4-20mA 4-20mA 2-Wire, Select Product
      • SI231 Signal Isolator
      • SI239 Signal Isolator
      • Select Product
    • 4-20mA 4-Wire
      • 4-20mA 4-20mA 4-Wire, Select Product
      • SL332 Signal Isolator
      • SL335 Signal Splitter
      • SL339 Signal Isolator
      • SSP235 Signal Splitter
      • HVI237 5KV Isolator
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • SI139 Signal Isolator
      • Select Product
    • dc mA/V 3-Wire
      • 4-20mA dc mA/V 3-Wire, Select Product
      • SI231 Signal Isolator
      • SI239 Signal Isolator
      • Select Product
    • dc mA/V 4-Wire
      • 4-20mA dc mA/V 4-Wire, Select Product
      • SL332 Signal Isolator
      • SL335 Signal Splitter
      • SL339 Signal Isolator
      • SSP235 Signal Splitter
      • HVI237 5KV Isolator
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • SI139 Signal Isolator
      • Select Product
    • Bipolar
      • 4-20mA Bipolar, Select Product
      • BSI234 Bipolar Signal Isolator
      • BSC133 Bipolar Signal Converter
      • BSI134 Bipolar Signal Isolator
      • Select Product
    • High Drive
      • 4-20mA High Drive, Select Product
      • BSC133 Bipolar Signal Converter
      • BSI134 Bipolar Signal Isolator
      • PD121 Power Driver
      • PD122 Power Driver
      • Select Product
    • Pulse/ Frequency
      • 4-20mA Pulse/ Frequency, Select Product
      • APC258 Analogue to Pulse Converter
      • PWM157 Analog To PWM
      • Select Product
    • Relay
      • 4-20mA Relay, Select Product
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • Select Product
    • Resistance
      • 4-20mA Resistance, Select Product
      • ATR167 Analog To Resistance
      • ATP168 Analog to Potentiometer
      • Select Product
    • Select Output
  • ac A
    • ac A, Select Output
    • 4-20mA 2-Wire
      • ac A 4-20mA 2-Wire, Select Product
      • ACT241 ac Current Transducer
      • Select Product
    • 4-20mA 4-Wire
      • ac A 4-20mA 4-Wire, Select Product
      • SL345 AC and Bipolar Isolator
      • DCT247 Dc Current Transducer
      • ACT284 ac Transducer
      • ACT141 ac Current Transducer
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • Select Product
    • dc mA/V 3-Wire
      • ac A dc mA/V 3-Wire, Select Product
      • ACT241 ac Current Transducer
      • Select Product
    • dc mA/V 4-Wire
      • ac A dc mA/V 4-Wire, Select Product
      • SL345 AC and Bipolar Isolator
      • DCT247 Dc Current Transducer
      • ACT284 ac Transducer
      • ACT141 ac Current Transducer
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • Select Product
    • Bipolar
      • ac A Bipolar, Select Product
      • BSC133 Bipolar Signal Converter
      • Select Product
    • High Drive
      • ac A High Drive, Select Product
      • BSC133 Bipolar Signal Converter
      • Select Product
    • Pulse/ Frequency
      • ac A Pulse/ Frequency, Select Product
      • APC258 Analogue to Pulse Converter
      • Select Product
    • Relay
      • ac A Relay, Select Product
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • Select Product
    • Select Output
  • ac V
    • ac V, Select Output
    • 4-20mA 2-Wire
      • ac V 4-20mA 2-Wire, Select Product
      • SI239 Signal Isolator
      • AVT245 ac Voltage Transducer
      • Select Product
    • 4-20mA 4-Wire
      • ac V 4-20mA 4-Wire, Select Product
      • SL345 AC and Bipolar Isolator
      • SL350 Pulse Frequency Transmitter
      • ACT284 ac Transducer
      • AVT145 Ac Voltage Transmitter
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • SI139 Signal Isolator
      • Select Product
    • dc mA/V 3-Wire
      • ac V dc mA/V 3-Wire, Select Product
      • SI239 Signal Isolator
      • AVT245 ac Voltage Transducer
      • Select Product
    • dc mA/V 4-Wire
      • ac V dc mA/V 4-Wire, Select Product
      • SL345 AC and Bipolar Isolator
      • SL350 Pulse Frequency Transmitter
      • ACT284 ac Transducer
      • AVT145 Ac Voltage Transmitter
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • SI139 Signal Isolator
      • Select Product
    • Bipolar
      • ac V Bipolar, Select Product
      • BSC133 Bipolar Signal Converter
      • Select Product
    • High Drive
      • ac V High Drive, Select Product
      • BSC133 Bipolar Signal Converter
      • Select Product
    • Pulse/ Frequency
      • ac V Pulse/ Frequency, Select Product
      • APC258 Analogue to Pulse Converter
      • Select Product
    • Relay
      • ac V Relay, Select Product
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • Select Product
    • Select Output
  • Conductivity
    • Conductivity, Select Output
    • 4-20mA 2-Wire
      • Conductivity 4-20mA 2-Wire, Select Product
      • CDT228 Conductivity Transmitter
      • Select Product
    • 4-20mA 4-Wire
      • Conductivity 4-20mA 4-Wire, Select Product
      • CDT128 Conductivity Transmitter
      • Select Product
    • dc mA/V 3-Wire
      • Conductivity dc mA/V 3-Wire, Select Product
      • CDT228 Conductivity Transmitter
      • Select Product
    • dc mA/V 4-Wire
      • Conductivity dc mA/V 4-Wire, Select Product
      • CDT128 Conductivity Transmitter
      • Select Product
    • Select Output
  • dc A
    • dc A, Select Output
    • 4-20mA 4-Wire
      • dc A 4-20mA 4-Wire, Select Product
      • SL345 AC and Bipolar Isolator
      • DCT247 Dc Current Transducer
      • SI139 Signal Isolator
      • Select Product
    • dc mA/V 4-Wire
      • dc A dc mA/V 4-Wire, Select Product
      • SL345 AC and Bipolar Isolator
      • DCT247 Dc Current Transducer
      • SI139 Signal Isolator
      • Select Product
    • Pulse/ Frequency
      • dc A Pulse/ Frequency, Select Product
      • APC258 Analogue to Pulse Converter
      • Select Product
    • Select Output
  • dc mA/V
    • dc mA/V, Select Output
    • 4-20mA 2-Wire
      • dc mA/V 4-20mA 2-Wire, Select Product
      • SI231 Signal Isolator
      • SI239 Signal Isolator
      • Select Product
    • 4-20mA 4-Wire
      • dc mA/V 4-20mA 4-Wire, Select Product
      • SL332 Signal Isolator
      • SL335 Signal Splitter
      • SL339 Signal Isolator
      • SL345 AC and Bipolar Isolator
      • SSP235 Signal Splitter
      • HVI237 5KV Isolator
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • SI139 Signal Isolator
      • Select Product
    • dc mA/V 3-Wire
      • dc mA/V dc mA/V 3-Wire, Select Product
      • SI231 Signal Isolator
      • SI239 Signal Isolator
      • Select Product
    • dc mA/V 4-Wire
      • dc mA/V dc mA/V 4-Wire, Select Product
      • SL332 Signal Isolator
      • SL335 Signal Splitter
      • SL339 Signal Isolator
      • SL345 AC and Bipolar Isolator
      • SSP235 Signal Splitter
      • HVI237 5KV Isolator
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • SI139 Signal Isolator
      • Select Product
    • Bipolar
      • dc mA/V Bipolar, Select Product
      • BSI234 Bipolar Signal Isolator
      • BSC133 Bipolar Signal Converter
      • BSI134 Bipolar Signal Isolator
      • Select Product
    • High Drive
      • dc mA/V High Drive, Select Product
      • BSC133 Bipolar Signal Converter
      • BSI134 Bipolar Signal Isolator
      • PD121 Power Driver
      • PD122 Power Driver
      • Select Product
    • Pulse/ Frequency
      • dc mA/V Pulse/ Frequency, Select Product
      • APC258 Analogue to Pulse Converter
      • PWM157 Analog To PWM
      • Select Product
    • Relay
      • dc mA/V Relay, Select Product
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • Select Product
    • Resistance
      • dc mA/V Resistance, Select Product
      • ATR167 Analog To Resistance
      • ATP168 Analog to Potentiometer
      • Select Product
    • Select Output
  • Environmental-z
    • Environmental-z, Select Output
    • 4-20mA 2-Wire
      • Environmental-z 4-20mA 2-Wire, Select Product
      • LUX510 LUX Transmitter
      • RTT508 Room Temperature Transmitter
      • RLT511 Room Light Transmitter
      • Select Product
    • dc mA/V 3-Wire
      • Environmental-z dc mA/V 3-Wire, Select Product
      • LUX510 LUX Transmitter
      • RTT508 Room Temperature Transmitter
      • Select Product
    • Select Output
  • mV
    • mV, Select Output
    • 4-20mA 2-Wire
      • mV 4-20mA 2-Wire, Select Product
      • MVT223 Millivolt Transmitter
      • SI239 Signal Isolator
      • Select Product
    • 4-20mA 4-Wire
      • mV 4-20mA 4-Wire, Select Product
      • SL340 Universal Transmitter
      • SSP235 Signal Splitter
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • SI139 Signal Isolator
      • Select Product
    • dc mA/V 3-Wire
      • mV dc mA/V 3-Wire, Select Product
      • MVT223 Millivolt Transmitter
      • SI239 Signal Isolator
      • Select Product
    • dc mA/V 4-Wire
      • mV dc mA/V 4-Wire, Select Product
      • SL340 Universal Transmitter
      • SSP235 Signal Splitter
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • SI139 Signal Isolator
      • Select Product
    • Bipolar
      • mV Bipolar, Select Product
      • BSI234 Bipolar Signal Isolator
      • Select Product
    • Pulse/ Frequency
      • mV Pulse/ Frequency, Select Product
      • APC258 Analogue to Pulse Converter
      • Select Product
    • Relay
      • mV Relay, Select Product
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • Select Product
    • Select Output
  • pH/REDOX
    • pH/REDOX, Select Output
    • 4-20mA 2-Wire
      • pH/REDOX 4-20mA 2-Wire, Select Product
      • PHT229 pH / Redox Transmitter
      • Select Product
    • 4-20mA 4-Wire
      • pH/REDOX 4-20mA 4-Wire, Select Product
      • PHT129 pH / Redox Transmitter
      • Select Product
    • dc mA/V 3-Wire
      • pH/REDOX dc mA/V 3-Wire, Select Product
      • PHT229 pH / Redox Transmitter
      • Select Product
    • dc mA/V 4-Wire
      • pH/REDOX dc mA/V 4-Wire, Select Product
      • PHT129 pH / Redox Transmitter
      • Select Product
    • Pulse/ Frequency
      • pH/REDOX Pulse/ Frequency, Select Product
      • APC258 Analogue to Pulse Converter
      • Select Product
    • Select Output
  • Position
    • Position, Select Output
    • 4-20mA 4-Wire
      • Position 4-20mA 4-Wire, Select Product
      • TPT194 Tap Position Transducer
      • Select Product
    • dc mA/V 4-Wire
      • Position dc mA/V 4-Wire, Select Product
      • TPT194 Tap Position Transducer
      • Select Product
    • Select Output
  • Potentiometer
    • Potentiometer, Select Output
    • 4-20mA 2-Wire
      • Potentiometer 4-20mA 2-Wire, Select Product
      • SWT240 Resistance Transmitter
      • Select Product
    • 4-20mA 4-Wire
      • Potentiometer 4-20mA 4-Wire, Select Product
      • SL340 Universal Transmitter
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • SI139 Signal Isolator
      • Select Product
    • dc mA/V 3-Wire
      • Potentiometer dc mA/V 3-Wire, Select Product
      • SWT240 Resistance Transmitter
      • Select Product
    • dc mA/V 4-Wire
      • Potentiometer dc mA/V 4-Wire, Select Product
      • SL340 Universal Transmitter
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • SI139 Signal Isolator
      • Select Product
    • Bipolar
      • Potentiometer Bipolar, Select Product
      • BSI234 Bipolar Signal Isolator
      • BSC133 Bipolar Signal Converter
      • BSI134 Bipolar Signal Isolator
      • Select Product
    • High Drive
      • Potentiometer High Drive, Select Product
      • BSC133 Bipolar Signal Converter
      • BSI134 Bipolar Signal Isolator
      • PD121 Power Driver
      • PD122 Power Driver
      • Select Product
    • Pulse/ Frequency
      • Potentiometer Pulse/ Frequency, Select Product
      • APC258 Analogue to Pulse Converter
      • Select Product
    • Relay
      • Potentiometer Relay, Select Product
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • Select Product
    • Resistance
      • Potentiometer Resistance, Select Product
      • ATR167 Analog To Resistance
      • ATP168 Analog to Potentiometer
      • Select Product
    • Select Output
  • Pressure
    • Pressure, Select Output
    • 4-20mA 2-Wire
      • Pressure 4-20mA 2-Wire, Select Product
      • PIC246 Pressure to Current Converter
      • Select Product
    • 4-20mA 4-Wire
      • Pressure 4-20mA 4-Wire, Select Product
      • PIC176 Pressure To Current Converter
      • Select Product
    • dc mA/V 3-Wire
      • Pressure dc mA/V 3-Wire, Select Product
      • PIC246 Pressure to Current Converter
      • Select Product
    • dc mA/V 4-Wire
      • Pressure dc mA/V 4-Wire, Select Product
      • PIC176 Pressure To Current Converter
      • Select Product
    • Select Output
  • Resistance
    • Resistance, Select Output
    • 4-20mA 2-Wire
      • Resistance 4-20mA 2-Wire, Select Product
      • RT243 Resistance Transmitter
      • Select Product
    • 4-20mA 4-Wire
      • Resistance 4-20mA 4-Wire, Select Product
      • SL340 Universal Transmitter
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • Select Product
    • dc mA/V 3-Wire
      • Resistance dc mA/V 3-Wire, Select Product
      • RT243 Resistance Transmitter
      • Select Product
    • dc mA/V 4-Wire
      • Resistance dc mA/V 4-Wire, Select Product
      • SL340 Universal Transmitter
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • Select Product
    • Bipolar
      • Resistance Bipolar, Select Product
      • BSC133 Bipolar Signal Converter
      • Select Product
    • High Drive
      • Resistance High Drive, Select Product
      • BSC133 Bipolar Signal Converter
      • Select Product
    • Pulse/ Frequency
      • Resistance Pulse/ Frequency, Select Product
      • APC258 Analogue to Pulse Converter
      • Select Product
    • Relay
      • Resistance Relay, Select Product
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • Select Product
    • Resistance
      • Resistance Resistance, Select Product
      • ATR167 Analog To Resistance
      • ATP168 Analog to Potentiometer
      • Select Product
    • Select Output
  • RTD
    • RTD, Select Output
    • 4-20mA 2-Wire
      • RTD 4-20mA 2-Wire, Select Product
      • RTDT225 RTD Temperature Transmitter
      • Select Product
    • 4-20mA 4-Wire
      • RTD 4-20mA 4-Wire, Select Product
      • SL340 Universal Transmitter
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • Select Product
    • dc mA/V 3-Wire
      • RTD dc mA/V 3-Wire, Select Product
      • RTDT225 RTD Temperature Transmitter
      • Select Product
    • dc mA/V 4-Wire
      • RTD dc mA/V 4-Wire, Select Product
      • SL340 Universal Transmitter
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • Select Product
    • Bipolar
      • RTD Bipolar, Select Product
      • BSC133 Bipolar Signal Converter
      • Select Product
    • High Drive
      • RTD High Drive, Select Product
      • BSC133 Bipolar Signal Converter
      • Select Product
    • Pulse/ Frequency
      • RTD Pulse/ Frequency, Select Product
      • APC258 Analogue to Pulse Converter
      • Select Product
    • Relay
      • RTD Relay, Select Product
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • Select Product
    • Resistance
      • RTD Resistance, Select Product
      • ATR167 Analog To Resistance
      • ATP168 Analog to Potentiometer
      • Select Product
    • Select Output
  • Signal Powered
    • Signal Powered, Select Output
    • 4-20mA 4-Wire
      • Signal Powered 4-20mA 4-Wire, Select Product
      • STI136 Single Trippoint Isolator
      • Select Product
    • dc mA/V 4-Wire
      • Signal Powered dc mA/V 4-Wire, Select Product
      • STI136 Single Trippoint Isolator
      • Select Product
    • Relay
      • Signal Powered Relay, Select Product
      • STI136 Single Trippoint Isolator
      • Select Product
    • Select Output
  • Speed/ Frequency/ Pulse
    • Speed/ Frequency/ Pulse, Select Output
    • 4-20mA 2-Wire
      • Speed/ Frequency/ Pulse 4-20mA 2-Wire, Select Product
      • FRT250 Frequency Transmitter
      • Select Product
    • 4-20mA 4-Wire
      • Speed/ Frequency/ Pulse 4-20mA 4-Wire, Select Product
      • SL350 Pulse Frequency Transmitter
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • RAF185 Ramp Function
      • Select Product
    • dc mA/V 3-Wire
      • Speed/ Frequency/ Pulse dc mA/V 3-Wire, Select Product
      • FRT250 Frequency Transmitter
      • Select Product
    • dc mA/V 4-Wire
      • Speed/ Frequency/ Pulse dc mA/V 4-Wire, Select Product
      • SL350 Pulse Frequency Transmitter
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • RAF185 Ramp Function
      • Select Product
    • Bipolar
      • Speed/ Frequency/ Pulse Bipolar, Select Product
      • BSC133 Bipolar Signal Converter
      • Select Product
    • High Drive
      • Speed/ Frequency/ Pulse High Drive, Select Product
      • BSC133 Bipolar Signal Converter
      • Select Product
    • Pulse/ Frequency
      • Speed/ Frequency/ Pulse Pulse/ Frequency, Select Product
      • PLS257 Pulse Splitter
      • APC258 Analogue to Pulse Converter
      • Select Product
    • Relay
      • Speed/ Frequency/ Pulse Relay, Select Product
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • Select Product
    • Resistance
      • Speed/ Frequency/ Pulse Resistance, Select Product
      • ATR167 Analog To Resistance
      • ATP168 Analog to Potentiometer
      • Select Product
    • Select Output
  • Strain Gauge
    • Strain Gauge, Select Output
    • 4-20mA 2-Wire
      • Strain Gauge 4-20mA 2-Wire, Select Product
      • WT227 Strain Gauge Transmitter
      • Select Product
    • 4-20mA 4-Wire
      • Strain Gauge 4-20mA 4-Wire, Select Product
      • SL340 Universal Transmitter
      • WT127 Strain Gauge Transmitter
      • Select Product
    • dc mA/V 3-Wire
      • Strain Gauge dc mA/V 3-Wire, Select Product
      • WT227 Strain Gauge Transmitter
      • Select Product
    • dc mA/V 4-Wire
      • Strain Gauge dc mA/V 4-Wire, Select Product
      • SL340 Universal Transmitter
      • WT127 Strain Gauge Transmitter
      • Select Product
    • Select Output
  • Thermocouple
    • Thermocouple, Select Output
    • 4-20mA 2-Wire
      • Thermocouple 4-20mA 2-Wire, Select Product
      • TCT226 Thermocouple Transmitter
      • Select Product
    • 4-20mA 4-Wire
      • Thermocouple 4-20mA 4-Wire, Select Product
      • SL340 Universal Transmitter
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • TCT286 Thermocouple Transmitter/Isolator
      • Select Product
    • dc mA/V 3-Wire
      • Thermocouple dc mA/V 3-Wire, Select Product
      • TCT226 Thermocouple Transmitter
      • Select Product
    • dc mA/V 4-Wire
      • Thermocouple dc mA/V 4-Wire, Select Product
      • SL340 Universal Transmitter
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • TCT286 Thermocouple Transmitter/Isolator
      • Select Product
    • Bipolar
      • Thermocouple Bipolar, Select Product
      • BSC133 Bipolar Signal Converter
      • Select Product
    • High Drive
      • Thermocouple High Drive, Select Product
      • BSC133 Bipolar Signal Converter
      • Select Product
    • Relay
      • Thermocouple Relay, Select Product
      • DTI135 Dual Trippoint Isolator
      • STI136 Single Trippoint Isolator
      • Select Product
    • Resistance
      • Thermocouple Resistance, Select Product
      • ATR167 Analog To Resistance
      • ATP168 Analog to Potentiometer
      • Select Product
    • Select Output
  • Select an Input (above)
  • Select Input

Select products that include a Transmitter function.

Transmitter Function

Transmitter Function

Auxiliary Powered Transmitter Concept

The signal transmitter converts a low level signal from any sensing device into a standardised process signal. These transmitters sometimes incorporate electromechanical devices such as strain gauges for measurement of physical values - pressure, flow, level, etc.

Signal transmitters can;

  • Convert one specific type of signal into another type of signal
    Input: Thermocouple type J 0-800°C
    Output: 4-20mA.
    May provide galvanic isolation from one signal (input) to another (output).
    Note that APCS defines a Signal Isolator as a transmitter with isolation.

When choosing a a transmitter please consider the following;

  • Input signal or measurement.
  • Output and what powers the signal conditioning module are a major determining factor when choosing a transmitter.
  • Is isolation required?

Calibration, Offset and Span

Most transmitters have two adjustments in common which are termed OFFSET (zero) and SPAN (gain). These adjustments allow the output signal to be varied considerably, generally 20% of the transmitter range.

The principle used in the calibration of transmitters is that if two points on a straight line are established then the line itself is established.

By examining Figure 2 it can be seen that at low magnitudes of input signal the effect of span adjustment is very small. Consequently the first calibration point should be selected close to the bottom of the input range. The offset adjustment is then used to give the required output signal for the input signal being fed to the transmitter.

Because alteration of the span results in a higher output deviation at the top end of the input range it follows that the second calibration point should be at this top end, say in the top 25%. Thus the calibration at this point is achieved by imposing an input signal of suitable magnitude and adjusting the span potentiometer to give the correct output.

In practice it is sometimes difficult to eliminate the interaction effects between offset and span so it is recommended that the procedure for setting these two points be repeated until both points are obtained without the need for further adjustments.

The Offset Adjustment sets what is in effect the value of output when the input is zero.

Figure 1 shows the effect of altering the offset of a transmitter.

Fifure 1 Offset Adjustment

Fifure 1 Offset Adjustment

Figure 2 Span Adjustment

Figure 2 Span Adjustment

The Span Adjustment alters the slope of the relationship between input and output signals.

Figure 2 shows the effect of altering the span of a transmitter.

The principle used in the calibration of transmitters is that if two points on a straight line are established then the line itself is established. By examining Figure 2 it can be seen that at low magnitudes of input signal the effect of span adjustment is very small. Consequently the first calibration point should be selected close to the bottom of the input range. The offset adjustment is then used to give the required output signal for the input signal being fed to the transmitter.

Because alteration of the span results in a higher output deviation at the top end of the input range it follows that the second calibration point should be at this top end, say in the top 25%. Thus the calibration at this point is achieved by imposing an input signal of suitable magnitude and adjusting the span potentiometer to give the correct output.

In practice it is sometimes difficult to eliminate the interaction effects between offset and span so it is recommended that the procedure for setting these two points be repeated until both points are obtained without the need for further adjustments.

 

  • Transmitter
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  • Transmitter Function
  • Calibration, Offset and Span
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