7i76e Communication errors

You can certainly try but the symptoms don't really suggest a full 5V loss
(that would cause loss of the Ethernet link), but just a problem with the on card
serial link between the FPGA side and the field I/O side

Another possibility is field power dropping out for a short time

So I would check the connections on TB1 and if you want to try applying 5V to P3 make sure you
disconnect your 19V power from TB3

another thing to try is an alternate field power supply

I just received a brand new 7i76e (ordered & delivered in Jan 2019) and am getting the exact messages as sliptonic:

hm2/hm2_7i76e.0 smart serial port 0
hm2/hm2_7i76e.0 Smart Serial Comms Error: There have been more than 1 errors in 10 thread executions at least 200 times.
hm2/hm2_7i76e.0 smart serial port 0 local error = (3) Timeout
hm2/hm2_7i76e.0 smart serial port 0 local error = (13) Communication error

As soon as this happens the CR1 led goes on and CR2 led is never one. CR3 through CR6 continue to flash.

My W1 is LEFT (single power). I have 24V connected to TB1 (pin5+, pin8-) and TB3 (pin22+, pin23-) show in attachment. There are no other connections on the board yet. I do measure 5V across stepper signals (such as: TB2-1 & TB2-6). With scope attached I have never been able to see any pulses on the step or direction pins.

I am always able to ping the board with no problems and when I run mesaflash with --readhmid I am able to read data from the board and it does seem to have swversion 14. I will post that along later tonight when I'm back fiddling with it.

I have had these errors from the beginning and I have never gotten this card to work. This is my first time working with linuxcnc and any mesa card so my natural inclination is that I'm doing something wrong. This is the only thread that I have found that even mentions these Serial Port 0 errors.

Can anyone think of something else that I should check before I call Mesa?

My guess would be that you have a latency issue on the host PC causing the FPGA side watchdog to bite

I would check the status of the watchdog-has-bit pin

Also posting your hal/ini files may help pinpoint setup issues

Ahhhh I'm going to bet that is it. I'm running from an old laptop (I'm too almost ashamed to admit). While it is directly connected, I'm sure that the ethernet chipset is not very good and likely doesn't have good linux support, and bad power management interference, etc. I knew this would come back to bight me. I'll report back my results tonight.

Thanks!!

SUCCESS!

For documentation purposes here was my problem:
I was using an older laptop machine which initially showed "workable" max jitter of 90,000ns without any tweaking or tuning and running normal test loads as described here . This was far from perfect, but enough to get some motors turning.

HOWEVER, I would occasionally see a spike to > 6,000,000ns. Being a new to linuxcnc I dismissed this as anomalies and when I didn't see any of these in a multi-hour test run I convinced myself that it wasn't a big deal and that I would look into it later.

So what was happening is exactly as PCW described. Those rare spikes of delay were actually very consistent when my computer would attempt to connect to the 7i76e board. That would cause the watchdog to flip and eventually loose the serial connection. The watchdog has_bit was true. In my case I could even flip this to false and it would run for a while then fail again.

I replaced the laptop with another machine that, after 5 minutes of tuning (I found this thread helpful), had 45,000ns of max latency with no spikes. The latency-plot tool was very helpful.

I know this was totally a noob problem, so thanks for the help. I chose to make a linuxcnc based machine because I wanted to actually know and understand the details of my machine and I am not disappointed.

This also points out a LinuxCNC hostmot2 driver bug in LinuxCNC 2.7:

watchdog bites do not pop up a notifier

This has been fixed in version 2.8