Mesa modbus and pktUart

Unless you get RX data echoed from TX data if /RE is grounded
and DE is asserted this has nothing to do with the 7I92 and likely
a wiring or hardware issue.

I manage to Echo RX/TX only if TXena is active low

 

 

 

It does not look like the servo drive is replying any data.

 

1. That's active high TXEN (high when transmitting as expected)
2. The middle picture ( A,B )  doesn't seem to show any data
( if its at the same time per division as the other plots )
in fact it looks like the TXEN signal

If i zoom time in to 10ms per grid line(I think) :

 

I am using linuxCNC 2.9pre on raspberry i build latetest build and copied hostmot2.so and hm2_eth.so to make pktuart to work, could that cause problems ?

I would say there are still hardware issues
(idle line state is undefined)

 A must be high and B low when no one is driving the RS-485 bus
That's the reason for the 620 Ohm pullup on A and 620 Ohm pulldown on B