Transmitter-Board-Only

Supported Applications

The ACI Transmitter Board Only Series is a temperature transmitter supplied as a bare board for integration with an existing sensor. It provides a two-wire, 4 to 20 mA loop-powered output, with optional three-wire voltage outputs available, and is designed to be used with an existing 100 or 1000 Ohm Platinum RTD that has a 385 temperature coefficient. Sensors are not included, so the board is intended for OEMs and integrators who already have a compatible RTD in place.

Because the transmitter is calibrated to a specified temperature span, it is well suited to embedding inside equipment, panels, and custom enclosures where a compact, board-level signal conditioner is needed. Each transmitter must be ordered with the temperature span required for the application, and the sensor type must be specified at the time of order. For harsher environments, potted versions encapsulate the board in a thermally conductive epoxy for added moisture and corrosion protection while helping dissipate heat evenly across the assembly.

Operating Conditions & Performance

The transmitter supports calibrated temperature spans from a minimum of 50°F (28°C) to a maximum of 1000°F (538°C), with best accuracy in 100°F increments. Calibrated accuracy and linearity are ±0.2% for temperature spans below 500°F (260°C) and ±0.5% for spans above 500°F (260°C). Temperature drift is ±0.04%/°F for spans below 100°F (38°C) and ±0.02% for spans above that, referenced to a nominal calibration temperature of 71°F (22°C). Warm-up time is 10 minutes with a ±0.1% warm-up drift.

The board accepts a Platinum RTD with a PTC (positive temperature coefficient) curve to DIN EN 60751 (IEC 751); the A/TT100 series accepts a nominal 100 Ohms @ 32°F (0°C) sensor and the A/TT1K series a nominal 1000 Ohms @ 32°F (0°C) sensor. Output is a 4 to 20 mA two-wire loop-powered current signal, or a three-wire 1 to 5 VDC or 2 to 10 VDC voltage signal.

Supply is +8.5 to 32 VDC (reverse-polarity protected) at 25 mA minimum. The available supply window rises with loop resistance: a 250 Ohm load requires +13.5 to 32 VDC and a 500 Ohm load requires +18.5 to 32 VDC. Connections are made on screw terminal blocks (polarity sensitive) for 16 AWG to 26 AWG wire, with a nominal terminal-block torque of 0.37 ft-lb.

The transmitter operates over -40°F to 185°F (-40 to 85°C) and is rated for storage over -40 to 80°C (-40 to 176°F), with an operating humidity range of 0 to 90% non-condensing. The board measures 2.30” (58.42 mm) by 1.478” (37.54 mm) by 0.775” (19.69 mm). It is RoHS2 and WEEE compliant.

Configuration Options

Models are built to the pattern A/ - Sensor Series - Configuration - Output Signal - Calibrated Span, with additional configuration suffixes. The main capability choices are:

• Sensor series: TT100 accepts a 100 Ohm Platinum RTD, while TT1K accepts a 1000 Ohm ("1K") Platinum RTD; both are BO (Board Only) configurations.
• Output signal: code 1 provides a 1 to 5 VDC output, code 2 provides a 2 to 10 VDC output, and code 4 provides a 4 to 20 mA output.
• Configuration options: the -POTTED suffix adds the epoxy-encapsulated build for moisture and corrosion protection, and enclosure suffixes such as -4X and -BB package the board for the corresponding housing; the calibrated span is specified per order.

Across all builds the electrical performance, accepted sensor type, and output options are the same; the differences are the RTD resistance the board is set for, the chosen output, and whether the board is potted or housed.

Key Product Differences

The series is offered in the following configured models:

• A/TT100-BO-1 — TT100 board only, 1 to 5 VDC output.
• A/TT100-BO-2 — TT100 board only, 2 to 10 VDC output.
• A/TT100-BO-4 — TT100 board only, 4 to 20 mA output.
• A/TT100-BO-4-4X, A/TT100-BO-4-4X-POTTED, A/TT100-BO-4-POTTED — TT100 boards with 4 to 20 mA output and enclosure and/or potted options.
• A/TT1K-BO-1 — TT1K board only, 1 to 5 VDC output.
• A/TT1K-BO-2, A/TT1K-BO-2-POTTED — TT1K, 2 to 10 VDC output, standard or potted.
• A/TT1K-BO-4, A/TT1K-BO-4-POTTED, A/TT1K-BO-4-4X-POTTED, A/TT1K-BO-4-BB-POTTED — TT1K boards with 4 to 20 mA output and potted and enclosure options.

In every case the calibrated temperature span is specified when the transmitter is ordered.