Intermittent serial connection

I've been having problems with intermittent serial connection / read time out errors. I use Argo serial 2 at 9600 baud, Meade startup protocol on com 1, via db9 serial port using Argo serial cable. I am connecting to Meade planetarium (Autostar Suite), on an old laptop running Windows XP. Sometimes it connects no problem, sometimes it won't connect at all, and sometimes it connects for a period then issues a read timeout error?

I'm assuming the problem is at the laptop end, which is also running cameras drawing power from the two available USB ports. Do you think this is a power issue, or something else?

Anyone had this problem, any ideas?
Thanks in anticipation, Tom

Hi Tom,

Thanks for the post and welcome to the forum.

The Argo Navis serial port communication is extremely robust and well tested, so it is most likely to be at the laptop end.

We've tested against Autostar extensively over the years but I just ran Austostar 3.18 on a Windows 2000 machine interfaced to an Argo Navis for half an hour and the connection didn't drop.

Make sure on the Autostar end in the communications dialog that you set parity to none and flow control to none.

I gather from your description the laptop has an in-built DB-9 COM port?

For the cameras drawing power from the USB ports, if the laptop manufacturer had complied with the USB specification, it should be able to
deliver sufficient power to them without interfering with the operation of anything else.

Given it is an older laptop though, is there any indication that is running out of grunt to process the data from the cameras and Autostar?
One test would be to disconnect the cameras and see if there is any improvement to the reliability of the serial comms.

Argo Navis serial ports 1 and 2 are independent and so another test would be to configure SERIAL 1 to run the 'meade' STARTUP command at 9600
and try swapping the cable to it.

Thanks for your suggestions. No joy on Serial 2, but have reconfigured serial 1 as you suggest and this appears to be working OK without usb cameras attached - I’ll test it tonight as clear skies. Does that mean there is a problem with Serial 2, dirty connection?

The laptop is an old Dell Latitude with Pentium M if you can still remember these. During lockdown I restored by original DEC Digital 386 25SL 2 Mb RAM and 40MB HDD and VGA display! I can still run my original Distant Suns from floppy disks...

tomrgray wrote:Thanks for your suggestions. No joy on Serial 2, but have reconfigured serial 1 as you suggest and this appears to be working OK without usb cameras attached - I’ll test it tonight as clear skies. Does that mean there is a problem with Serial 2, dirty connection?

The laptop is an old Dell Latitude with Pentium M if you can still remember these. During lockdown I restored by original DEC Digital 386 25SL 2 Mb RAM and 40MB HDD and VGA display! I can still run my original Distant Suns from floppy disks...

Have a look inside the SERIAL 2 port under good light and magnification. Check that the contacts are clean and are all sitting in the same plane.

Also have a look inside the battery compartment and check if there has been any sign of a battery having leaked or vented in the past.

If you have a multimeter, put it in continuity mode or resistance measuring mode. Power the unit off. Use Appendix C of the User Manual to identify which is the SERIAL 1 GND contact.
Try and probe it and the GND contact of the External DC Power Port for low impedance. If there has ever been a short on the SERIAL 1 line, it may have blown the associated protective ferrite.