Key Features:

The TT238 model is a two-wire transmitter that isolates and converts a high level DC voltage input to a proportional 4-20mA control signal. It provides flexibility as this unit supports both voltage and current input .the Power is received from the output loop current or a DC supply when using a three-wire connection

• Easy setup and digital calibration via USB with Windows configuration software
• Single unit supports ±15V, ±75V, and ±150V DC input ranges
• Space-saving 12.5mm (0.5 inch) unit with pluggable terminals for convenient wiring
• High accuracy, linearity, stability, and reliability
• User-selectable filtering (low, medium, high)
• Supports sink or source output wiring
• Supports reverse-acting (inverse) output
• Selectable upscale or downscale operation for sensor errors and lead-break detection
• 1500V input isolation
• NAMUR-compliant output loop current
• Shock (50g) and vibration (5g) resistant
• Mounts on Type T DIN-rail
• Wide ambient operation (-40 to 80°C)
• CE compliant. UL/cUL Class 1 Div 2 Zone 2 approvals

Product Details

USB Interface

USB Connector
– Type: USB Mini-B type socket, 5-pin.
– Data rate: 12Mbps. USB v1.1 and 2.0 compatible.
– Maximum cable length: 5.0 meters.
USB Transient Protection
– Transient voltage suppression on power and data lines.
– Not required. Uses Windows HID drivers.


Default Configuration
– Pot/slidewire, 0% to 100% input, 4-20mA output, downscale break detect, medium filter.
Input Configuration
– Two- or three-wire sensor input connections.
– User-configurable thermistor linearization table has preset curves for resistances below at 25°C.
– Programs in °C, °F, °K, or ohmic integer values only.
Lead Break (Sensor Burnout) Detection
– Configurable for either upscale or downscale on thermistor or rheostat inputs. Downscale only on potentiometer/slidewire inputs.
Excitation Voltage
– Thermistor/rheostat: 1.25V DC, typical.
– Potentiometer: 0.3V DC, limited to 3.35mA, typical.


Output Accuracy
– Better than ±0.05% of span, typical (±0.1% max.)
– for for nominal input spans. Includes the effects of repeatability, terminal point conformity, and linearization, but does not include sensor error.
Output Load
– Voltage output: 1K ohms minimum.
– Current output: 0-525 ohms.
Output Response Time (for step input change)
– No filter: 21ms.
– Medium filter: 150ms.
– Low filter: 40ms.
– High filter: 1200ms.
– Output Ambient Temperature Drift Better than ±80ppm/°C (±0.0080%/°C).


Operating temperature
– -40 to 80°C (-40° to 176°F).
Storage temperature
– -40 to 85°C (-40 to 185°F).
Relative humidity
– 5 to 95% non-condensing.
Power Requirement
– 12-32V DC SELV (Safety Extra Low Voltage), 1.3W max.
– 1500V AC peak. 250V AC (354V DC) continuous
– isolation between input, output, and power (3-way).
Shock and Vibration Immunity
– Vibration: 4g, per IEC 60068-2-64.
– Shock: 25g, per IEC 60068-2-27
- CE compliant. UL/cUL Class I Div. 2 Zone 2..
Electromagnetic Compatibility (EMC) Compliance
- Radiated Emissions: BS EN 61000-6-4, CISPR 16.
– RFI: BS EN 61000-6-2, IEC 61000-4-3.
– Conducted RFI: BS EN 61000-6-2, IEC 61000-4-6.
– ESD: BS EN 61000-6-2, IEC 61000-4-2.
– EFT: BS EN 61000-6-2, IEC 61000-4-4.
– Surge Immunity: BS EN 61000-6-2, IEC 61000-4-5.


– General-purpose enclosure designed for mounting on 35mm “T-type” DIN rail.
Case Material
– Self-extinguishing polyamide, UL94 V-0 rated, color light gray. General-purpose NEMA Type 1 enclosure.
I/O Connectors
– Removable plug-in terminal blocks rated for 12A/250V; AWG #26-12, stranded or solid copper wire.