TT351: Strain Gauge Input Four-Wire Transmitter

The TT351 model is a space-saving four-wire transmitter that converts a four or six wire strain gauge bridge or load cell or milliVolt sensor signal to an isolated voltage or current output signal. An optional DIN rail bus can deliver primary or redundant power to multiple units.

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

The transmitter’s input circuit allows true 6-wire bridge measurement and includes an adjustable bridge excitation supply (4 to 11V DC) with a remote sense feature. Sense wires ensure the programmed excitation voltage is measured at the sensor and enable lead-wire compensation. The differential input performs true ratiometric conversions for extremely stable measurements that remain accurate over time and temperature.

Advanced signal processing capabilities, variable range input, and convenient USB programming make this instrument a very versatile strain/load 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 use of their USB-ISOLATOR when configuring a TT350 Series transmitter.

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.

Driver
Not required. Uses Windows HID drivers.

General Input

Analog to Digital Converter (ADC)
24-bit S-D A/D converter.

Resolution
Varies from 13.5 to 20.5 bits per filter and gain selection.

Input Reference Test Conditions
Strain gauge/mV; Excitation = 10V; Rated Output = 1mV/V; Range = ±10mV; Ambient Temperature = 25°C; Power Supply = 24V DC.

Accuracy (overall input to output)
Better than ±0.1% of span, typical. This value does not include sensor errors.

Ambient Temperature Effect
Better than 0.008% of input span per °C (±80ppm/°C).

Noise Rejection
Normal mode @ 60Hz: -19dB (no filter), -34dB (low filter), >80dB (med/high filter).
Common mode @ 60Hz: -136dB, typical with 100 ohm input unbalance.

Input Overvoltage Protection
Bipolar Transient Voltage Suppressors (TVS).

Bridge Input

Input Types
Select from basic load cell, two quarter-bridge options, two half-bridge options, three full-bridge options, or milliVolts.

Input Span/Range
Bipolar input range is determined from the ± product of the gauge’s rated output and the nominal excitation selection (2mV/V x 10V = ±20mV range).

Input Over-range
The actual input range is up to (user-specified) ±150% of the range obtained via the ± product of the gauge’s rated output and the nominal excitation applied.

Input Sensitivity
Accepts gauge rated outputs up to 1mV/V to 10mV/V. The range of your input signal is the ± product of the excitation voltage and your gauge’s rated output.

Input Impedance
±IN at 15M ohms, ±SEN at 73.2K ohms, typical.

Input Lead Resistance
Module has sufficient overdrive to guarantee 10V bridge excitation with 5 ohms/lead and 100mA of internal excitation current. Larger lead resistances may limit the maximum achievable internal bridge excitation.

Input Bridge Excitation (Internal)
Adjustable from 4V to 11V, 120mA maximum. Internal excitation must be turned OFF before external excitation supply connection.

Input Bridge Excitation (External)
4V to 11V. The internal excitation must be turned OFF for connection to an external excitation supply.

Digital (Trigger) Input

Input Type
“Active High” input, 100ms minimum.

15-30V DC (6.65K ohms).
See connection diagram.

Operation (Tare/Alarm Modes)
The trigger function is set for “Auto-Tare” mode by default.

Output (DC V/mA)

D/A Converter
16-bit.

Current Output
Ranges: 0-20mA, 4-20mA.
Compliance: 10V minimum (525 ohm load).

Voltage Output
Ranges: 0-5V, ±5V, 0-10V, ±10V.
Compliance: 10mA maximum with short circuit protection. 1 ohm output impedance.

Output Response Time to 98% (for step input change)
No filter: 264ms. Medium filter: 472ms.
Low filter: 292ms. High filter: 2547ms.

Environmental

Operating temperature
-40 to 70°C (-40° to 158°F)

Storage temperature
-40 to 85°C (-40 to 185°F)

Relative humidity
5 to 95% non-condensing.

Power Requirement

Supply |    Ptot   | Current Draw
9V         | 3.05W | 339mA Max.
12V       | 3.05W | 254mA Max.
15V       | 3.05W | 203mA Max.
24V      | 3.05W | 127mA Max.
32V      | 3.05W | 95mA Max.

Isolation
4-way (input/output/trigger/power). Input/excitation, analog output, trigger, and power circuits are isolated from each other for up to 1500V AC for 60 seconds or 250V AC continuous.

Shock and Vibration Immunity
Vibration: 4g.
Shock: 25g.

Approvals (pending)
CE compliant. UL/cUL listed Class I Division 2 Groups ABCD. ATEX, IECEx certified 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
17.5 x 114.5 x 99.0 mm (0.7 x 4.51 x 3.90 inches).

Shipping Weight
0.22 kg (0.5 pounds) packed.