7B32 Isolated, Process Current Input


7b32-01-1The 7B32 is a single-channel signal conditioning module that interfaces, amplifies and filters a process-current input and provides a protected precision output voltage of either +1 V to +5 V or 0 V to +10 V. Process-current input signals are measured by reading the voltage across an internal 200 Ω protected resistor. Model 7B32 features a nonlinearity of ±0.02% maximum and an accuracy of ±0.1% maximum (±0.01% typical). To accurately measure low level signals in electrically noisy environments, 1500 V rms of galvanic transformer-based isolation with a common mode rejection (CMR) of 105 dB @ 50/60 Hz is provided. Rated to operate with a nominal +24 V DC supply, Model 7B32 is mix-and-match and hot-swappable with other 7B Series input modules, so it can be inserted or removed from any socket in the same backplane without disturbing system power.

Inside the 7B32 Series Module

The floating current input of Model 7B32 is fully protected up to 120 V rms line voltage. A one-pole 100 Hz filter preconditions the voltage signal across the 200 Ω protected input resistor prior to amplification by a low drift amplifier. Amplitude modulation is used to implement transformer isolation (1500 V rms input-to-output and power). Isolated front-end circuitry power is supplied by a DC/DC converter. The output section contains a two-pole low pass filter (-3 dB @100 Hz), a buffer amplifier and a power oscillator. The two-pole output filter and subsequent buffer ensures that a low noise, low impedance (<1 Ω) signal is available at the output to drive loads to 2 kΩ minimum.

Input and Output Ranges

7B32 Functional Block Diagram 

Figure 1. 7B32 Functional Block Diagram

7B32 Input Field Connections

Figure 2. 7B32 Input Field Connections

Input Types Output Options 
4 mA to 20 mA
0 to 20 mA
+1 V to +5 V
0 V to +10 V

View and Order Models

Input Range  Output Range 
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+4 mA to +20 mA
+1 V to +5 V
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7B32-01-2 0 mA to +20 mA
0 V to +10 V


7B32 Specifications
(typical @ +23°C ±5°C and Vs = +24 V dc)

Model 7B32
Input Ranges1
Standard Ranges 4 mA to 20 mA; 0 mA to 20 mA 
(Refer to Model Table)
 Custom Ranges  Not Available*
Output Range Options (RL > 2 kΩ)
+1 V to +5 V or 0 V to +10 V
Initial @ +25°
±0.01% Span (±0.1% Span, maximum)
Nonlinearity2 ±0.02% Span, maximum
Input Offset vs. Temperature  N/A3
Span vs. Temperature  ±35 ppm/°C
Output Offset vs. Temperature  ±0.003% span/°C
 Input Resistance
Power ON  200 Ω
Power OFF 200 Ω, minimum
 Output Noise
5 MHz Bandwidth  6 mV peak
10 Hz to 100 kHz Bandwidth
0.4 mV rms
0.1 Hz to 10 Hz Bandwidth
3 µV peak
Bandwidth, -3 dB 3 Hz
Output Rise Time, 10% to 90% Span
150 ms
 Common-Mode Voltage (CMV)
 Input-to-Output and Power
1500 V rms continuous 
Common-Mode Rejection (CMR) 
Input-to-Output and Power @ 50/60 Hz
105 dB
Input Protection 120 V rms, continuous
±35 V dc, continuous
Input Transient Protection ANSI/IEEE C376.90.1-1989
IEC 255-4, Class II
Output Resistance < 1 Ω
Voltage Output Protection Continuous Short to Ground 
 Power Supply
 Voltage Range, Operating  +14 V dc to +35 V dc
 +25 mA, maximum
 ±0.0001%/% of Vs
Mechanical Dimensions 1.663" x 2.11" x 0.563
(42.24 mm x 53.6 mm x 14.3 mm)
Weight 60 grams
 Temperature Range
  Operating  -40°C to +85°C
  Storage  -40°C to +85°C
 Relative Humidity, 24 hours
 0 to 90% @ +60°C noncondensing
 ESD Sensitivity
 IEC 801-2, Level 2
 RFI Susceptibility  ±0.5% Span error @ 400 MHz, 5 Watt, 3 ft

Warm-up time required to meet specifications is approximately 10 minutes.
* Contact factory for OEM requirements.
1 Includes the combined effects of repeatability, hysteresis, and nonlinearity.
2 Nonlinearity is calculated using best-fit straight line method.
3 Vz is the nominal input voltage that results in a 0 V output.
Specifications subject to change without notice.