latest INDI/Ekos/Kstars, version 2.8.9 Build: 2017-12-25T02:08:08Z

I am getting disconnects happening that I cannot figure out. I am guiding using the internal guider (finally figured that out - other thread updated). After some time, in this case one 180s exposure in and one about 60s, the mount stops responding to guide commands and stops tracking. I go in to the INDI control panel and hit the disconnect button 2x, and then reconnect and it is back to working, thought the capture session needs to be set up again. Is this something new, or maybe just a cold stiff cable type issue that is pulling on a port? Would it be possible to trap and display the unrecognized error code to help debugging?

2017-12-27T03:55:31: [ERROR] Error when disconnecting mount -> tty write failed, check connection: Error: unrecognized error code
2017-12-27T03:55:31: [ERROR] Error: -> tty write failed, check connection: Error: unrecognized error code
2017-12-27T03:55:31: [ERROR] Error when disconnecting mount -> tty write failed, check connection: Error: unrecognized error code
2017-12-27T03:55:31: [ERROR] Error: -> tty write failed, check connection: Error: unrecognized error code
2017-12-27T03:55:31: [ERROR] Error when disconnecting mount -> tty write failed, check connection: Error: unrecognized error code
2017-12-27T03:55:31: [ERROR] Error: -> tty write failed, check connection: Error: unrecognized error code
2017-12-27T03:55:31: [INFO] EQMod Mount is offline.
2017-12-27T03:55:31: [ERROR] Error: -> tty read failed, check connection: Timeout error
2017-12-27T03:48:04: [INFO] Telescope slew is complete. Tracking TRACK_SIDEREAL...
2017-12-27T03:48:03: [INFO] Iterative Goto (1): RA diff = 1.48 arcsecs DE diff = 0.05 arcsecs
2017-12-27T03:48:02: [INFO] Slewing to RA: 6:41:56 - DEC: 9:39:37
2017-12-27T03:48:02: [INFO] Slewing mount: RA increment = 1678, DE increment = 3262
2017-12-27T03:48:02: [INFO] Starting Goto RA=6.69899 DE=9.66021 (current RA=6.85556 DE=7.52569)
2017-12-27T03:47:54: [INFO] Telescope slew is complete. Tracking TRACK_SIDEREAL...
2017-12-27T03:47:54: [INFO] Iterative Goto (2): RA diff = 1.15 arcsecs DE diff = 0.13 arcsecs
2017-12-27T03:47:52: [INFO] Iterative goto (1): slew mount to RA increment = 609, DE increment = 0
2017-12-27T03:47:52: [INFO] Iterative Goto (1): RA diff = 5.76 arcsecs DE diff = 0.13 arcsecs
2017-12-27T03:47:47: [INFO] Slewing to RA: 6:42:11 - DEC: 9:31:54
2017-12-27T03:47:47: [INFO] Slewing mount: RA increment = 26604, DE increment = -285
2017-12-27T03:47:47: [INFO] Starting Goto RA=6.70317 DE=9.53177 (current RA=6.92576 DE=7.53706)
2017-12-27T03:47:35: [INFO] Mount is unparked.
2017-12-27T03:47:35: [WARNING] Init() : Setting both ST4 guide rates to 0.5x (2)
2017-12-27T03:47:35: [WARNING] Init() : Setting default Init steps -- RAInit=8388608 DEInit = 8388608
2017-12-27T03:47:35: [WARNING] Init() : Motors already initialized
2017-12-27T03:47:35: [INFO] EQMod Mount is online.
2017-12-27T03:47:35: [INFO] Successfully connected to EQMod Mount.

Update: does not appear to be a cable issue. I stopped trying to guide, and so far have 5 frames of 180 seconds with no time-outs. There does seem to be something here to look into. Is the first step to capture the error information being reported but not recognized ?

Update 2: even this failed after some more time.

@knro (or anyone with the dev environment set up), can we get a quick change to dump the raw messages when the error is unknown instead of printing "Error: unrecognized error code" in EQmod?

In my experience it's been one of two things.
1. Cable issue. Check both ends. I have found the USB end to be a failure point and needed to be pinched to make better contact. Give it a wiggle to see.
2. Voltage drop off to the mount during slew. Make sure batteries are well charged, more likely to occur in the cold.

Both of these are likely candidates, I agree. I have done much to prevent voltage drop, using a 12v constant voltage 12A power supply, and short runs to the mount, but in the cold, the cables are stiff either way, and so, more prone to have tension on them. The USB end is in an enclosure with the computer and is very well protected from both cold and movement, but the RJ end is certainly exposed.

I would like to see the actual error returned to see if it might help pinpoint where to fortify.

99% of the time it's the connection. The USB had me puzzled for a long time because it would disconnect when I slew, it looked like any number of possible issues, driver, power, connection. etc. Turned out it was how the USB fit, just a slight wiggle could break the connection.