Remove Modbus_NoParityRequiresTwoStopBits and modify Parity default value

Apollo3zehn / FluentModbus

Lightweight and fast client and server implementation of the Modbus protocol (TCP/RTU).

MIT License

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Remove Modbus_NoParityRequiresTwoStopBits and modify Parity default value #56

Closed maikebing closed 2 years ago

maikebing commented 3 years ago

…o None

rogerjak commented 2 years ago

Need this fix for a Riden Power Supply RD6006 that uses 8N1. Just finished migrating from EasyModbus when I realized FluentModbus didn't accept this... When will this be merged and released on Nuget? Thanks!

Apollo3zehn commented 2 years ago

Hi, I'll review it tomorrow.

Apollo3zehn commented 2 years ago

According to the spec (https://www.modbus.org/docs/Modbus_over_serial_line_V1_02.pdf), section 2.5.1 RTU Transmission Mode:

"The default parity mode must be even parity."
"... the use of no parity requires 2 stop bits."

So I think the devices are not working according to the Modbus specification. I will remove the error message to allow compatibility, but the default of the parity mode should be kept even to stay in line with the spec.

Apollo3zehn commented 2 years ago

I have pushed version 4.0.0-preview.2.final and 3.2.1 (backport) to Nuget. I hope its working now for both of you :)