Remora - ethernet NVEM / EC300 / EC500 cnc board

About the lack of transmission from my NVMPG:

I tried disassembling the MPG and taking some measurements.

To begin with: TX from Remora on NVME v5 to MPG is working fine, display is updated accordingly to LinuxCNC status. Only RX part, transmission from MPG to NVME is not there.

1. I tried plugging my scope directly to RX port on NVMPG internal board while without it being connected to NVME (TX, Vdd and GND are still attached to NVME and the display is updating) - see the `rx_floating.jpeg` image. I was getting correct (I guess) RS232 -5V/ 5V, similar to what was received on TX port (`rx_osci.jpeg`). 

 
 

2. Second test was to try connecting RX port to NVME with probe in line. Unfortunately, I was not able to observer any signal at all. See the connection:
 


Any ideas why it might be the case? It at least looks like pull-down resistor between RX and GND in my NVME is bad/short-circuited (if it is even present in this design?).
- Resistance between MPG's GND and RX on NVME is around 25 ohm (with board disconnected from power)
- For comparison, between COM and INP3 (that works as expected) I'm seeing around 45kOhm.

Have you checked to see if the RX/TX works at all like trying to output or print data through it and connect it to another device like arduino, pc, pi?

Will try to check that.

One more question that came to my mind: in Remora, does the pendant state is transmitted via RX/TX or the A+/A- and B+/B- pairs?
I'm asking because even though it seems that I might possibly have some issues with RX line, the AB pairs seem to correctly send spikes when pendant wheel is turned. This is for example B+ pin when turning pendant clockwise:
 

So, for pendant on MPG to work, you only connect RX/TX or also AB pairs?

I couldn't answer that for you I got no idea, but it should be in the config file, the code for the mpg module shows only TX/RX Pin 9 and Pin 10, but it looks like it only requires uart which means TX/RX for the mpg module, but I also believe the uart can be changed to other pins I have to double check that so don't quote me. Maybe we can make a custom bin with changed pins for UART.

slawekgonet wrote:

To begin with: TX from Remora on NVME v5 to MPG is working fine, display is updated accordingly to LinuxCNC status. Only RX part, transmission from MPG to NVME is not there.

 

When you say the "transmission from MPG to NVME is not there", what are you expecting? The serial communication for the MPG is used to update the display and receive button presses. The A and B pairs are directly wired to the handwheel encoder.

 

On TX pin I was expecting constant transmission of display updates - and I definitely see that with the scope.

On RX pin I can also see UART-like transmission with RS232 levels when there is a key press with RX line floating, but when I plug it to NVME it seems to be short-circuited to ground.

I can see encoder pulses on both A and B pairs also when plugged in to NVME, but LinuxCNC is not responding to these nor was I able to detect any reaction to that in HAL.