905U-L I/O Count Transmitter and Receiver Pair

Key Features:

The ELPRO 105U-L and 905U-L products are a small I/O count transmitter and receiver pair pre-configured for ease of installation. The L series products may be reconfigured into a wider ELPRO I/O or gateway network as application needs grow.

•865–867 MHz/902–928 MHz frequency and 1W RF power
• Link I/O inputs to single or multiple I/O outputs (peer to peer)
•Reliable point–to–multi-point two-way communications combining exception reporting, self-checking and data encryption
• Multi-hop repeater function provides increased communication distance
•Multiple I/O channels for monitoring and controlling field devices with set-point, pulse count, and rate available. Additional internal I/O points provided for health monitoring
•Communication failure notification and diagnostics, including radio path measurement, communications logging, and verification of I/O values
•Built-in low voltage AC/DC/battery power options, UPS battery charger and solar regulator
•User-friendly configuration software

Product Details

Transmitter and Receiver


865–867 MHz , 902–928 MHz , 915–928 MHz

Transmit power



 Frequency hopping spread spectrum (FHSS)


Frequency shift keying

Receiver sensitivity

–106 dBm @ 19.2 kbps

Channel spacing

50 x 250 kHz

Data rate

19.2 kbps

Range (LoS)

20 miles (32 km) @ 4W ERIP d

9.3 miles (15 km) @ 1W EIRP (other countries)

Antenna connector

1 x female SMA standard polarity

Input and Output

Digital input Voltage free/NPN, wetting current 0.5 mA

Surge protected (non-isolated)

905U-1: 4

905U-2: 4

905U-3: 0

905U-4: 4–16 inputs e

Digital output

905U-1: 4 relay contacts, AC 50V: 5 AC/DC 30V: 2A

905U-2: 1 FET output 30 Vdc/500 mA

905U-3: 8 FET output 30 Vdc/500 mA

905U-4: 4–16 FET outputs e

Analog input

Floating differential inputs, common mode voltage 27V

24 Vdc for external loops provided, digital filtering 1 second

905U-1: 2 current, 4–20 mA, 15-bit resolution, 0.1% accuracy, over range indication 2–25 mA

905U-2: 6 current, 0–20 mA, 12-bit resolution, 0.1% accuracy, over range indication 0–25 mA

Analog output

Current sink to common, max loop voltage 27V, max. loop resistance 1000 Ohms

905U-1: 2 current, 4–20 mA, 15-bit resolution, 0.1% accuracy, over range indication 0.5–25 mA

905U-3: 8 current, 0–20 mA, 12-bit resolution, 0.1% accuracy, over range indication 0–20.5 mA

Pulse input

As per digital input specifications above

Max. pulse rate 1000 Hz, pulse width min. 5 ms

905U-1: 1 pulse input, terminated at DI 1

905U-2: 4 pulse inputs, terminated at DI 1–4

905U-2: first DI/PI max. 1000 Hz, pulse width min. 0.5 ms

905U-2: DI/PI 2, 3, 4 max. 100 Hz, pulse width 5 ms

905U-4: 4 pulse inputs, terminated at DI 1–4

905U-4: first digital inputs/pulse inputs max 1000 Hz, pulse width min. 0.5 ms. 2, 3, 4 DI/PIs max 100 Hz, pulse width 5 ms

Pulse output

As per FET digital outputs specifications above FET DO/PO 30 Vdc/500 mA, max pulse rate 100 Hz

905U-1: 1 pulse output

905U-3: 4 pulse outputs, terminated at DO 1–4

905U-4: 4 pulse outputs, terminated at DO 1–4

Serial Port

RS-232 9-pin DB-9 female connector (for programming use only)

RS-485 2-pin terminal block f, serial expansion 4000′ (1.2 km)

Data rate (bps) 9600

Serial settings 7/8 data bits, no parity, 1 stop bit

Protocols and Configuration

System address

Configurable system address

Protocols supported

ELPRO WIBnet™ auto acknowledgement up to 4 retries, CRC error checking

Configurable parameters

Individual I/O mappings, analog and digital debounce, update time, analog set points and sensitivities, output reset times


64-bit encryption on radio and serial

LED Indication and Diagnostics

LED indication Power/OK, I/O status, OK/module OK, TX, RX  Reported diagnostics RSSI, comms logging, I/O status

Power Supply

Nominal supply

12–24 Vac/15–30 Vdc: over-voltage/reverse power protected

Average current draw

At 12 Vdc: 85 mA

+10 mA per active digital input

+25 mA per active digital output

2 x per analog I/O loop (mA)

Transmit current draw

350 mA @13.8 Vdc, 250 mA @ 24 Vdc

Battery supply 11.5–15.0 Vdc (battery supply volts internal I/O value)

Battery charging circuit

1.2–12 Ah battery: max. charge current 0.7A @ >12V

Solar regulator

Direct connection solar panel (to 30W)/solar battery 100 Ah

Loop supply

Internal DC/DC converter: 24 Vdc/150 mA current limited


EMC FCC Part 15

RF (radio) FCC Part 15.247, RSS 210, AS/NZS4268

Hazardous area CSA Class I, Division 2

Safety EN 60950