10 common problems and solutions for converting CAN to RS232

1.上电后设备无反应、指示灯不亮 
1. After power on, the device has no response and the indicator light does not light up 

-原因：供电电压不匹配、接线错误、电源无输出。 
-Reason: Mismatched power supply voltage, incorrect wiring, and no output from the power supply. 

-解决：确认模块为5V/9-24V供电，正负极不可接反；更换电源与电源线，测量供电端电压。 
-Solution: Confirm that the module is powered by 5V/9-24V and the positive and negative poles cannot be reversed; Replace the power supply and power cord, and measure the voltage at the power supply end. 

2.能发送数据但收不到数据 
2. Can send data but cannot receive data 

-原因：CAN/485方向控制异常、终端电阻未接、波特率不匹配。 
-Reason: CAN/485 direction control abnormality, terminal resistance not connected, baud rate mismatch. 

-解决：检查收发使能引脚配置；CAN总线两端接120Ω终端电阻；确保双方波特率、校验位一致。 
-Solution: Check the configuration of the enable pins for transmitting and receiving; Connect 120 Ω terminal resistors at both ends of the CAN bus; Ensure that the baud rate and checksum of both parties are consistent. 

3.数据乱码、丢包、不稳定 
3. Data garbled, packet loss, and instability 

-原因：波特率/帧格式不一致、干扰大、总线过长、接地不良。 
-Reason: Inconsistent baud rate/frame format, high interference, long bus, poor grounding. 

-解决：统一波特率与校验位；总线采用屏蔽线，单端接地；缩短总线距离，避开强电动力线。 
-Solution: Unify baud rate and checksum; The bus adopts shielded wire and is grounded at one end; Shorten the bus distance and avoid strong electric power lines. 

4.RS485通信只能单向 
4. RS485 communication can only be one-way 

-原因：收发切换延时不当、AB线接反、匹配电阻问题。 
-Reason: Inappropriate delay in transmitting and receiving switching, reverse connection of AB line, and matching resistance issues. 

-解决：对调485 A、B线；检查模块自动流向控制是否开启；减少总线分支。 
-Solution: Swap 485 A and B lines; Check if the automatic flow control of the module is enabled; Reduce bus branches. 

5.CAN总线报错误帧、离线 
5. CAN bus error frame, offline 

-原因：无终端电阻、波特率不匹配、多主机冲突。 
-Reason: No terminal resistance, mismatched baud rate, multiple host conflicts. 

-解决：两端必须加120Ω电阻；统一CAN波特率；避免多个节点同时主动发送。 
-Solution: 120 Ω resistors must be added at both ends; Unified CAN baud rate; Avoid multiple nodes actively sending at the same time. 

6.与PLC/上位机连不通 
6. Unable to connect with PLC/upper computer 

-原因：协议格式不匹配、ID过滤开启、地址错误。 
-Reason: Protocol format mismatch, ID filtering enabled, address error. 

-解决：关闭不必要的ID过滤；确认帧格式为标准/扩展帧；核对设备站号与协议。 
-Solution: Turn off unnecessary ID filtering; Confirm that the frame format is standard/extended frame; Verify the device station number and protocol. 

7.串口调试助手收不到数据 
7. The serial debugging assistant cannot receive data 

-原因：串口参数错、TX/RX接反、电平不兼容。 
-Reason: Incorrect serial port parameters, TX/RX reversed connection, incompatible voltage levels. 

-解决：确认波特率、数据位、停止位、校验位；对调TX、RX；232交叉直连。 
-Solution: Confirm baud rate, data bits, stop bits, and parity bits; Swap TX and RX; 232 cross direct connection. 

8.工业现场干扰大、死机 
8. Large interference and system crashes in industrial sites 

-原因：未隔离、共地电压差、布线不合理。 
-Reason: Failure to isolate, common ground voltage difference, and unreasonable wiring. 

-解决：选用带光电隔离模块；单点接地；动力线与信号线分开走线。 
-Solution: Choose a module with photoelectric isolation; Single point grounding; The power line and signal line are routed separately. 

9.多节点组网通信异常 
9. Abnormal communication in multi node networking 

-原因：总线拓扑混乱、分支过长、地址冲突。 
-Reason: Chaotic bus topology, excessively long branches, and address conflicts. 

-解决：采用手拉手总线，禁止星形；每个485/CAN总线上地址唯一。 
-Solution: Adopt a hand-in-hand bus and prohibit star shaped buses; Each address on the 485/CAN bus is unique. 

10.模块正常但上位机显示不更新 
10. The module is normal but the upper computer display does not update 

-原因：缓存未清空、超时设置不当、数据格式错误。 
-Reason: Cache not cleared, improper timeout setting, incorrect data format. 

-解决：清空接收缓存；合理设置串口超时；检查报文长度与校验规则。 
-Solution: Clear the receiving cache; Reasonably set serial port timeout; Check the message length and verification rules. 

如果您的项目需要用到CAN转RS232/485设备，可以加微信130193255660或前往沈阳广成科技官网具体咨询。 
If your project requires CAN to RS232/485 devices, you can add WeChat 130193255660 or visit the official website of Shenyang Guangcheng Technology for specific consultation.