Regarding whether multi-core cables can be used jointly for the DI and DO of electric valves

When using multi-core cables for the DI (digital input) and DO (digital output) of electric valves, it is important to ensure that circuits with different levels or voltage ranges do not share the same wires within the same cable. This is mainly to prevent electrical interference between components and to ensure the safe operation of the system. Different voltage levels generally refer to the differences in signal voltage, such as 24V DC, 220V AC, etc. In practical engineering applications, it is recommended to configure the cables according to the requirements of the equipment and relevant standards. If the specifications permit and it is reasonable from the standpoint of safety and operational efficiency, it is possible to use a multi-core cable in the same installation unit, provided that the various signals do not interfere with each other. In general, it is recommended to consult in detail regarding the specific project requirements and specifications, and to work closely with electrical design engineers to select the most appropriate wiring scheme. .

They cannot be shared; if DI and DO are in different IO cabinets, wouldn’t that require wires to be run between the cabinets?

It depends on the situation. If there are few devices on site and there is only one PLC control terminal cabinet, with AI, AO, DI, and DO all located in that same cabinet, multi-core cables can be used. These cables can then be routed to the site through conduits or cable trays, and on-site junction boxes can be added at appropriate locations. From these junction boxes, wires can be connected to the various signal terminals of one or more electric doors; proper labeling is all that’s needed. .

Feel free to use it together – our company has been using it this way for a long time; we use a 6-core cable with 2 DI and 1 DO connections. Previously they were separate, but the engineering department suggested combining them, and asked the manufacturer of the shut-off valve to make the changes. That manufacturer refused to do so, so we switched to another manufacturer. The 6-core cable is used for feedback purposes, the 4-core cable connects to the switch feedback, and the 2-core cable goes to the solenoid valve nearby.

The current of DO is 500 milliamps; there are also energy-saving versions with a current of around 150 milliamps. It is a direct current signal, so it doesn’t interfere with other devices, and it’s impossible for other devices to interfere with it. The DI signal is a signal of a few milliamps, and it is not easily disturbed by other signals; it also lacks the ability to interfere with others. After all, it is direct current, not a high-frequency alternating current signal. If the interference is severe, with dense traces on a single microcontroller, then the microcontroller can no longer function properly. If the isolation valve is located far from the control cabinet, it is recommended to use a cable with a cross-sectional area of 1.5 square millimeters; if it is nearby, 1 square millimeter is sufficient. Smaller cross-sectional areas are not allowed by regulations, and in explosion-proof areas, a cross-sectional area of less than 1 square millimeter is not permitted. DO is output through the power amplification board, while DI is output directly from the DI card. The best arrangement is to place the DO amplification board and the DI card in the same location. Since my workshop uses the 300 system from Zhejiang University Zhongkong, the chassis for the DI cards can be placed in the cabinet where the relay amplification board is located, which makes wiring easier.