ABB 07KR91 with part numbers GJR5250000R202 and GJR5250000R252 is a high-performance compact CPU module of Procontic CS31 and AC31 series. It is equipped with relay outputs, and can work as a standalone controller or bus master for medium-sized distributed automation systems.

07 represents Procontic 90/31 and AC31 product series. KR stands for CPU module with relay outputs. 91 refers to the high-performance version compared with 07KR31 and 07KR51.

This module supports two types of power supply including 24 VDC within 18 VDC to 30 VDC range and 115/230 VAC depending on specific models. The total physical memory is 30 kB and the available user program memory is 28 kB Flash EPROM. It has 20 channels of 24 VDC digital inputs supporting both sink and source modes, and 12 normally open relay outputs with rated current 10 A at 240 VAC. One 10 kHz high-speed counter input is integrated. It is fitted with two serial ports, COM1 is RS-232 interface and COM2 is RS-485 interface. It supports Modbus RTU, CS31 system bus and ASCII communication. The CS31 bus can connect up to 31 remote I/O modules. The maximum expansion capacity covers 744 digital inputs, 496 digital outputs, 96 analog inputs and 48 analog outputs. A built-in real-time clock is available for event timestamping. The operating temperature ranges from 0 degrees Celsius to 55 degrees Celsius. The overall dimensions are 160 mm in width, 100 mm in height and 95 mm in depth, and the weight is about 0.5 kg. The product has obtained CE, UL and CSA certifications.

Onboard LED indicators include PWR, RUN, ERR, TX and RX for operating status and fault diagnosis. The RS-232 interface is mainly used for program downloading, parameter configuration and point-to-point connection with human-machine interfaces. The RS-485 interface supports Modbus RTU master and slave modes and serves as CS31 system bus for multi-drop networking. Professional software 907 PC 331 or Control Builder AC31 is adopted for programming and configuration.

It executes control programs based on ladder logic and structured text, and supports PID control for independent operation. Acting as CS31 bus master, it expands system scale by connecting up to 31 remote slave I/O modules. It realizes data interaction with various devices via multiple serial communication protocols. The 10 kHz high-speed counter is applicable for processing pulse and encoder signals. With real-time clock and non-volatile storage, it achieves data recording and event timestamping.

It is widely applied to conveyors, assembly lines and packaging machinery in factory automation. It is suitable for process control such as water treatment plants and pumping stations. It also works for large HVAC systems and energy management in building automation. In addition, it is a preferred replacement and upgrade component for legacy Procontic CS31 systems.

The module can be installed on standard 35 mm DIN rail or control panels. Use shielded twisted pair cables for RS-485 and CS31 bus wiring, and separate signal cables from high-power cables. The 07LE90 memory module can be used for program backup. Regularly check the state of LED indicators, and back up user programs every year. The power circuit is designed with reverse polarity protection. Once faults occur, check power supply and wiring first, and troubleshoot communication parameters and bus connection if needed.