User manual for the Hongrun OHR-E740 Series four-loop digital display controller, covering installation, wiring, setup, and parameter configuration.
The OHR-E740 Series four-loop digital display controller uses surface-mount production and is described as having strong anti-interference capability. It accepts multiple signal types and can be paired with sensors and transmitters to measure and display temperature, pressure, liquid level, speed, force, and other physical quantities. It displays four measurement signals at once and can provide eight separate alarm outputs or four separate transmission outputs, plus RS485/232 communication.
The manual covers technical parameters, installation dimensions and wiring, the display panel and function keys, power-on setup, and primary and secondary parameter settings. It also describes parameter lock levels, alarm and calculation settings, communication baud rate, input type selection, and transmission output configuration. This manual is written in Chinese.
| Measurement accuracy | 0.2%FS ±1 digit |
|---|---|
| Display range | -1999 to 9999 |
| Power supply | AC/DC 100–240 V; DC 20–29 V |
| Operating temperature | -10 to 50 °C |
| Operating humidity | ≤85%RH |
| Communication | Standard MODBUS; RS485 up to 1 km; RS232 up to 15 m |
| Relay output | AC220V/2A; DC24V/2A |
The stated measurement accuracy is 0.2%FS ±1 digit.
RS485 communication can reach up to 1 km using the standard MODBUS protocol.
Set Loc to 577, then in the Loc menu hold the two keys together for 4 seconds.
After 30 seconds, the meter automatically returns to the real-time measurement screen.