TT231: RTD / Resistance Input Two-Wire Transmitter

The TT231 model is a space-saving two-wire transmitter that converts a 100 ohm Platinum RTD sensor input to a proportional 4-20mA signal. Power is received from the output loop current or a DC supply when using a three-wire connection. The transmitter provides sensor excitation plus performs linearization, lead-wire compensation, and lead-break detection.

Setup and calibration are fast and easy with a convenient USB connection to your PC and Acromag’s Windows configuration software.

Advanced signal processing capabilities, variable range input, and convenient USB programming make this instrument a very versatile temperature measurement device. These transmitters can withstand harsh industrial environments and operate reliably across a wide temperature range with very low drift. They feature RFI, EMI, ESD, EFT, and surge protection plus low radiated emissions.

Performance Specifications

IMPORTANT: To prevent damage or errors from grounded PCs and surges, Acromag strongly recommends the use of their USB-ISOLATOR when configuring a TT230 Series transmitter.

USB Interface

USB Connector: USB Mini-B type socket, 5-pin.

USB Data Rate: 12Mbps. USB v1.1 and 2.0 compatible.

USB Transient Protection: Transient voltage suppression on power and data lines.

USB Cable Length: 5.0 meters maximum.

Driver: Not required. Uses built-in Human Interface Device (HID) USB drivers of the Windows operating system.

Input

Default Configuration: 100Ω Pt RTD, α=0.00385 Ω/Ω/°C, 0-200°C input, 4-20mA output, upscale break detection.

Input Configuration: Two-, three- or four-wire sensor input connections.

Input Ranges:
100 ohm Platinum RTD, alpha = 375-393, 385 (default), -50 to 850°C (-58 to 1562°F)
0 to 900 ohms linear resistance
Programs in °C, °F, or ohmic integer values only.

Zero Adjust:
RTD 3/4 wire: -50, -17.78, or 0°C (-58, 0, 32°F).
RTD 2 wire: 0°C (32°F) fixed.
RES: 0 or 100 ohms.

Full-Scale Adjust:
RTD: up to 850°C (1562°F), 50°C (58°F) span minimum.
Resistance: up to 900 ohms, 8 ohm span minimum.

Excitation Current: 0.5mA, nominal, each ± lead.

Lead-Wire Compensation: 25 ohms per lead.

Lead Break (Sensor Burnout) Detection: Configurable for either upscale or downscale.

Input Filter Bandwidth: -3dB at 700Hz, typical, normal mode filter.

Output

Output Range: 4 to 20mA DC.
Under-scale limit adjustable for 2.1 to 3.6mA, nominal.
Over-scale limit adjustable for 21 to 30mA, nominal.

Output Fault Limits (Sensor Fault): 0.4mA below selected under-scale threshold and 1.0mA above over-scale threshold, typical.

Output Compliance:
Rload = (Vsupply – 8.6V) / 0.020A.
Rload = 0 to 750 ohms @ 24V DC.

Output Accuracy: Better than ±0.1% of span, typical for spans less than 500°C. Includes the effects of repeat-ability, terminal point conformity, and linearization, but does not include sensor error.

Ambient Temperature Effect: Better than ±0.008% per °C of input span or ±80ppm/°C, typical. Includes the combined effects of zero and span drift over temperature.

Output Response Time (for step input change): 500μS, typical with 250 ohm load (to reach 98% of final output value).

Environmental

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: 9-32V DC SELV (Safety Extra Low Voltage), 30mA max.

Shock and Vibration Immunity:
Vibration: 4g, per IEC 60068-2-6
Shock: 25g, per IEC 60068-2-27

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.

Approvals:
CE compliant. Designed for UL/cUL Class I Division 2 Groups ABCD, ATEX / IECEx Zone 2. II 3 G Ex nA IIC T4 Gc -40°C < Ta < +80°C.

Physical

General: 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.

Dimensions: 12.5 x 114.5 x 99.0 mm (0.5 x 4.51 x 3.90 inches).

Shipping Weight: 0.22 kg (0.5 pounds) packed.