AC-3U-250 TELKOOR

COM port communication is not normal

Fault phenomenon: when communicating with other COM port equipment RS-485, it can not be sent or received, or it can not be sent, etc.

Fault analysis: Usually, when programming COM communication, it is necessary to judge the communication state of COM port in advance. Make sure that you can send data when it&＃39;s valid and receive data when it&＃39;s valid. This is called RTS communication. However, in order to facilitate programming and speed up program execution

some users did not confirm the COM port communication state before designing the hardware, and did not pay attention to the query transceiver state during programming, which is also called AUTO communication mode. Considering its versatility, usually the motherboard with COM port is RTS communication, so when used for RS-485 communication, there will be a can send can not receive or can not receive the fault phenomenon

Solution: The simplest solution to this problem is to use the EVOC product Ark-14520 (RS232 to RS485 module). However, if it is the communication between the COM port on the motherboard, usually there will be no such problem.

2.2 LCD display is not bright

Fault phenomenon: when the case on power, LCD display without any response;

Failure analysis: the direct cause of this failure is that the LCD backlight is not lit. After the maintenance personnel used a multimeter to measure the input power supply voltage of the backlight drive panel inverter

they found that +12V was not input. When the input power supply of the backlight drive panel was cut off, the voltage was normal. It is judged that the fault is caused by short circuit of +12V power supply on the backlight drive plate.

Solution: remove the backlight drive plate with short circuit problem from the chassis, and then power it on, so that the problem can be effectively solved. If necessary, some protective measures should be taken for the backlight drive panel to avoid such problems again.