Needs mode for Master & Slave on single channel

[timreyes]

Specifically, we should have a combined mode, called "Modbus/RTU - Master & Slave", which auto-detects the messages on a single data line as either Master or Slave. Modbus can have both Master & Slave messages on a single line.

The simplest solution is to try both decodings modes (master and slave) for each decoded frame (single blue decoded box) – the correct one for is the one with a valid Checksum.

[david-vankampen]

I believe this should be mostly addressed in #3 - I had issues using the failing checksum, so I just added a flag indicating whether it was processing a request or a response.

[timreyes]

The same issue might have been reported here too: https://discuss.saleae.com/t/modbus-analyzer/2024/2

[ghost]

@timreyes & @david-vankampen

Is there a fix for this yet? I am working with modbus and have no way to see the response from a device. Every message is considered a Server or Client. You need both call and response to properly understand what is happening on the bus.

Notice the "invalid checksum" in the attached image. The analysis on the Saleae's part is incorrect because the server is actually responding properly with a valid checksum. (CRC-16 assumed)

[RTU]>Tx > 15:01:56:189 - 01 03 00 80 00 02 C5 E3
[RTU]>Rx > 15:01:56:205 - 01 03 04 0D F2 07 BC 5A ED

[david-vankampen]

@sgal-powerbreezer it looks like #3 is still pending. I will bump that one.

[ghost]

thank you🙏