1. What is a communication protocol?
A communication protocol is an agreement between two parties to a communication. The agreement includes uniform provisions on data format, synchronization mode, transmission speed, transmission steps, error detection and correction mode, and control character definition, etc., which must be complied with by both parties to the communication. Therefore, it is also called the communication control procedure, or transmission control procedure, which belongs to the data link layer in the ISO'SOSI seven-layer reference model. Hollysys supports ProfiBus, FF, CanOpen, Lonworks, etc
2. What should I do if there is a problem with the on-site signal?
The problems of on-site signals are mainly as follows
Bad measuring element;
transmitter failure;
Connection problems, including signal wire reverse, loose, disconnected, grounding during transmission, and interference during transmission that is affected by interference coupling beyond the system can accept, etc.
In short, from signal measurement, transmission, to MACS terminals, any error in the link will result in incorrect data display.
3. How to check for hardware failure?
Hardware failures often manifest themselves in the following ways
The plug-in board of the module is not tightly plugged into the bus baseplate;
DIP switch error; The communication line is wired in the wrong direction;
The terminal matcher is not connected;
The type of hardware jumper does not match the actual signal requirements;
The system power supply and field power output in the cabinet are incorrect;
The hardware itself is bad.
The results of the above problems are as follows:
After powering on, the hardware board pole is faulty (the indicator light shows the wrong status);
The device is not working;
The system is working, but the displayed corresponding measurement point value is incorrect, the output of the system cannot drive the field device, and so on.
4. How to deal with software errors?
Problems arise due to incorrect coordination between software configuration and hardware
The configuration of the database point does not match the field signal connected to the corresponding channel;
The mouse driver is added to the COM1 port, which makes the system unable to be operated with the mouse when it is running online.
The printer does not print, etc.
5. What problems should I pay attention to when changing the connection joint?
Connector issues
The connector is not welded or the welding is not good, resulting in virtual welding;
Thermal cycling loosens the joint;
Loosening of bolted joints due to vibration;
Poor contact at the connection points due to corrosion.
6. What are the aspects of power failure?
Power issues
Power supply problems are divided into power connection problems and power quality problems.
Problems with the power supply
Including: no connection (fire, earth, zero items, one of which is not connected); Incorrect connection (live wire and neutral wire reversed, ground wire and neutral wire reversed, ground wire and neutral multipoint short).
Power quality issues
Including: the quality of the equipment connection (each connector is loose); The technical indicators (voltage, frequency, etc.) exceed the specified requirements.
Line quality issues
Including: increased impedance of the power cord and poor insulation.
The problem of the poles
Including: the resistance of the ground pole increases, and the earth pole is disconnected from the ground grid.
Environmental issues
Including: the wiring of the power cord, especially the ground wire, is unreasonable, and the wires and equipment that produce strong magnetic field interference are too close.
7. What should I do if the data of an input channel is abnormal?
Solution: Disconnect the field signal of this channel from the terminal of the I/O module, send a signal with the analog signal source and add the same signal as this field signal to this channel, and observe whether the displayed value on the CRT returns to normal. If it is normal, it means that the problem is on the side of the field signal, and it can be found and solved according to the method mentioned above; If it is still abnormal, the problem is caused by the MACS system.
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