RS485 non standard data word

tasifacij · ‎2024-10-03

Hi,

uc: stm32f446

I have a question regarding non standard word length over RS485.

I need to receive next frame over RS485

1 start bit, 16-bit data word, 2 stop bits, in total 19 bits.

UART implementation allows to receive 8 or 9-bit data words.

Could you please advice what can be an approcach to achieve?

Best regards, Taras.

zhaowhong · ‎2024-10-11

This chip is sp3845

Andrew Neil · ‎2024-10-14

@zhaowhong wrote:
This chip is sp3845

That's just an RS485 transceiver; that has nothing to do with the data frame format - just the voltages used to represent the bit states.

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.

tasifacij · ‎2024-10-14

You are quite right - in this particular case we have voltages and edge detection.

Andrew Neil · ‎2024-10-14

So, again, what was your basis for saying, "The real product does not do this"

What does the "real product" do?

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.

tasifacij · ‎2024-10-14

I had a uart with non-standard word length( 16 bits ). This is all it does.

Andrew Neil · ‎2024-10-14

Sorry, it was @zhaowhong who said, "The real product does not do this"

But can't you give any more detail of what you do have than just, "Fanuc encoder"?

A part number? A link to a datasheet or Product Page? Anything??

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.