485 sends data but receives data intermittently

有刁民想刺杀朕

485 sends data but receives data intermittently [Copy link]

I captured the data through the 485 serial port

Here is my data:

The data starting with 03 and 04 on the left are sent. Normally, they should be responded directly. However, there are many times when the data cannot be responded or received. What is the reason? I am almost driven crazy.

[2022-01-05 12:29:02.640]# RECV HEX>
03 02 03 00 00 02 33 1A

[2022-01-05 12:29:02.925]# RECV HEX>
04 02 03 00 00 02 33 1A

[2022-01-05 12:29:04.223]# RECV HEX>
03 02 03 00 00 02 33 1A 03 03 00 01 00 11 08 11

[2022-01-05 12:29:04.494]# RECV HEX>
04 02 03 00 00 02 33 1A 04 03 00 01 00 11 08 11

[2022-01-05 12:29:05.780]# RECV HEX>
03 02 03 00 00 02 33 1A 03 03 00 01 00 11 08 11

[2022-01-05 12:29:06.051]# RECV HEX>
04 02 03 00 00 02 33 1A 04 03 00 01 00 11 08 11

[2022-01-05 12:29:07.304]# RECV HEX>
03 02 03 00 00 02 33 1A 03 03 00 01 00 11 08 11

[2022-01-05 12:29:07.577]# RECV HEX>
04 02 03 00 00 02 33 1A 04 03 00 01 00 11 08 11

[2022-01-05 12:29:08.840]# RECV HEX>
03 02 03 00 00 02 33 1A

[2022-01-05 12:29:09.128]# RECV HEX>
04 02 03 00 00 02 33 1A 04 03 00 01 00 11 08 11

[2022-01-05 12:29:10.385]# RECV HEX>
03 02 03 00 00 02 33 1A

[2022-01-05 12:29:10.673]# RECV HEX>
04 02 03 00 00 02 33 1A 04 03 00 01 00 11 08 11

[2022-01-05 12:29:11.944]# RECV HEX>
03 02 03 00 00 02 33 1A

[2022-01-05 12:29:12.233]# RECV HEX>
04 02 03 00 00 02 33 1A 04 03 00 01 00 11 08 11

[2022-01-05 12:29:13.498]# RECV HEX>
03 02 03 00 00 02 33 1A

[2022-01-05 12:29:13.769]# RECV HEX>
04 02 03 00 00 02 33 1A 04 03 00 01 00 11 08 11

[2022-01-05 12:29:15.043]# RECV HEX>
03 02 03 00 00 02 33 1A

[2022-01-05 12:29:15.325]# RECV HEX>
04 02 03 00 00 02 33 1A 04 03 00 01 00 11 08 11

[2022-01-05 12:29:16.605]# RECV HEX>
03 02 03 00 00 02 33 1A 03 03 00 01 00 11 08 11

[2022-01-05 12:29:16.878]# RECV HEX>
04 02 03 00 00 02 33 1A 04 03 00 01 00 11 08 11

[2022-01-05 12:29:18.150]# RECV HEX>
03 02 03 00 00 02 33 1A 03 03 00 01 00 11 08 11

[2022-01-05 12:29:18.406]# RECV HEX>
04 02 03 00 00 02 33 1A 04 03 00 01 00 11 08 11

[2022-01-05 12:29:19.690]# RECV HEX>
03 02 03 00 00 02 33 1A 03 03 00 01 00 11 08 11

[2022-01-05 12:29:19.962]# RECV HEX>
04 02 03 00 00 02 33 1A 04 03 00 01 00 11 08 11

[2022-01-05 12:29:21.218]# RECV HEX>
03 02 03 00 00 02 33 1A

[2022-01-05 12:29:21.506]# RECV HEX>
04 02 03 00 00 02 33 1A 04 03 00 01 00 11 08 11

[2022-01-05 12:29:22.770]# RECV HEX>
03 02 03 00 00 02 33 1A

[2022-01-05 12:29:23.042]# RECV HEX>
04 02 03 00 00 02 33 1A

[2022-01-05 12:29:24.342]# RECV HEX>
03 02 03 00 00 02 33 1A 03 03 00 01 00 11 08 11

[2022-01-05 12:29:24.585]# RECV HEX>
04 02 03 00 00 02 33 1A

[2022-01-05 12:29:25.885]# RECV HEX>
03 02 03 00 00 02 33 1A 03 03 00 01 00 11 08 11

[2022-01-05 12:29:26.125]# RECV HEX>
04 02 03 00 00 02 33 1A

[2022-01-05 12:29:27.429]# RECV HEX>
03 02 03 00 00 02 33 1A 03 03 00 01 00 11 08 11

[2022-01-05 12:29:27.669]# RECV HEX>
04 02 03 00 00 02 33 1A

[2022-01-05 12:29:28.954]# RECV HEX>
03 02 03 00 00 02 33 1A 03 03 00 01 00 11 08 11

[2022-01-05 12:29:29.225]# RECV HEX>
04 02 03 00 00 02 33 1A

[2022-01-05 12:29:30.979]# RECV HEX>
03 02 03 00 00 02 33 1A

[2022-01-05 12:29:31.278]# RECV HEX>
04 02 03 00 00 02 33 1A E2 78 E0 C1 E0 F7 E7

[2022-01-05 12:29:35.949]# RECV HEX>
04 02 03 00 00 02 33 1A 04 03 00 01 00 11 08 11

[2022-01-05 12:29:37.204]# RECV HEX>
03 02 03 00 00 02 33 1A

[2022-01-05 12:29:37.489]# RECV HEX>
04 02 03 00 00 02 33 1A 04 03 00 01 00 11 08 11

[2022-01-05 12:29:38.776]# RECV HEX>
03 02 03 00 00 02 33 1A 03 03 00 01 00 11 08 11

[2022-01-05 12:29:39.032]# RECV HEX>
04 02 03 00 00 02 33 1A 04 03 00 01 00 11 08 11

有刁民想刺杀朕

Because I set it to disconnect all operations if there is no response within ten seconds, so it is very uncomfortable to not receive a response all the time

yangjeff

I don't understand this, please explain.

有刁民想刺杀朕

yangjeff posted on 2022-1-5 13:23 I don't understand this, hope you can explain it,

There are three devices. One host sends data to the other two at an interval of 250ms. The other two devices receive the data and send back a response data.

The two slaves use a 20ms timer to receive data. As a result, sometimes the data is not received after each transmission, or sometimes the host cannot receive the response data sent by the slave.

damiaa

modbus?

chunyang

How do you determine that the data cannot be received? Use a serial port monitoring software to check the data at the TTL end of the receiving side. If there is a problem with the data, it is a problem with the sender or the transmission line. If there is no problem with the data, it is an error in the receiving side software.

Gen_X

RS485 signals must be biased, otherwise they often have a beginning but no end and the signal is disordered.