FM148C HollySys Power Module, Shanghai Sijian Intelligent Technology Co., Ltd. is engaged in technology development, technical consultation, technology transfer, and sales of electrical equipment, automation equipment, electronic products, communication products, and electromechanical products in the fields of intelligent technology, information technology, and automation technology. Industrial automation products: PLC, DCS, sensors, frequency converters, encoders, relays, servo drives, soft starters, touch screens. Brands involved in the products include: Eurotherm, Schneider, Siemens, ABB, SICK, P+F, E+H, Yokogawa, Yamakawa, Mitsubishi, Emerson, Honeywell, FANUC, GE, Eaton Electric, CT. HollySys FM148C is an 8-channel current (voltage) type analog input module.
The wiring requirements for the fm148c terminal signals require each channel signal to use two-wire cables connected to the terminal block of the base   fm148c
For current input signals, the fm148c has two wiring methods: two-wire current signal wiring as shown, four-wire current signal wiring as shown in 2. For voltage signals, there is only one wiring method: voltage signal wiring as shown. Four-wire field device cable Two-wire field device cable i0+  
FM148C HollySys Power Module, Field cable layer I/O device Field cable layer I/O device  
fm148c two-wire current signal connection n2~7 fm148r four-wire current signal connection n2~7  
1 Related knowledge see fm148c manual  
2 Related knowledge see fm148c manual  
In the application of DCS systems, to prevent multiple grounding points from causing issues, in 50% of fault diagnosis problems, errors are basically caused by power supply, air source, and hydraulic source problems. For example, power supply issues, including failures of the entire workshop's power supply, such as damaged power supply power, poor contact of power plugs, etc.; air pumps or hydraulic pumps not started, pneumatic triple units or double units not started, unloading valves or certain pressure valves in hydraulic systems not opened, etc. These basic problems are usually common issues.
Check if the sensor position has shifted
Due to the negligence of equipment maintenance personnel, the positions of some sensors may be incorrect, such as not in place, sensor failure, sensitivity failure, etc. Regularly check the sensing position and sensitivity of sensors, adjust in time if deviations occur, and replace immediately if the sensor is broken. Often, if the power supply, air source, and hydraulic source are ensured to be error-free, more problems are sensor failures. Especially for magnetic induction sensors, due to long-term use, internal contacts may stick together and cannot separate, resulting in a normally closed signal, which is a common issue with this type of sensor and can only be replaced. In addition, due to equipment vibration, most sensors may become loose after long-term use, so during daily maintenance, regularly check if the sensor position is correct and firmly fixed.
Check relays, flow control valves, pressure control valves
Like magnetic induction sensors, relays may also experience contact adhesion after long-term use, thus failing to ensure the normal operation of electrical circuits and requiring replacement. In pneumatic or hydraulic systems, the throttle opening and pressure regulating springs of pressure valves may also become loose or slide due to equipment vibration. These devices, like sensors, are components that require daily maintenance in the equipment.