View Full Version here: : Meade Gurus (ie AndrewJ)
29-05-2012, 07:30 AM
I have a Scope Stuff LX200GPS data cable 5 meters long. It is wired same as the one in my observatory that I bought years ago from Scope Stuff.
When I plug the new one into either of my LX200 a message comes back - cannot detect device error 203. So I figure something else is buggered inside the cable. This cable is round and heavily shielded. I can easily make up a new 5 meter cable from flat 4 core telephone line, BUT does it need to be shielded?
29-05-2012, 07:44 AM
I used to use a 20m CAT5 cable for my LX200GPS (plus serial adaptor) and it worked flawlessly. It was well in excess of the length I needed, but there didn't seem to be any need to trim it down to size as it just worked.
29-05-2012, 08:25 AM
The LX200s use a bog std 3wire rs232 serial cable
sooooooooo, what is generating the error
"cannot detect device error 203." ????
If the scopestuff cable has an inbuilt usb2ser adapter,
then the problem "probably" lies between the PC and it.
Or, are you are using a third party usb2ser adapter???
If you plug in your cable ( but not to the scope )
and start my PEC editor, does it detect the adapter
as an "available" com port????
ie is the converter even being seen as a "com" port????
I regulary used a 30m length of 4wire flat phone cable
and i now use a cat5 cable with my rs232 for the scope
and camera feed for my webby run together
and it works quite happily.
Shielding shouldnt be required for your run length
More interested as to whats not playing
( ie what is "generating" the error )
29-05-2012, 10:40 AM
Thanks Dean and Andrew for your responses, sincerely appreciated.
I have checked the new Scope Stuff LX200 data cable and pins 2,3 & 5 are wired correctly to the RJ12 plug (exactly same as the existing cable that runs and works perfectly on the observatory scope). The pc & telescope are connected via a Keyspan serial adapter.
I am assuming the new cable has some other issue internally that causes the error message as it gives the same error message when connected to either scope.
You have answered what I was unsure about - whether I needed a shielded cable at 5 metres. So tonight I will make up a 5m cable using 4 core telephone wire and all should be well. Will discard the cable that doesn't work and let you know how the new cable works.
29-05-2012, 12:04 PM
Just a few other potential problems that I can brainstorm which may be worth investigating if you have no further luck:
* Which COM port numbers are the Keyspan adapters mapped to? The software may be expecting it to be a different number to what was auto assigned by Windows.
* Check whether the port settings (rate, parity, handshaking, stop/start bits, etc) are configured the same at the operating system level - in Device Manager. Software can (and should) override the OS defaults, but sometimes they don't. There are also other advanced settings (FIFO buffer length, send/receive latency, etc) that sometimes causes grief.
* Check whether the cable that works has any other pins shorted. Some devices will expect that RTS/CTS are active high (and won't work without them being set). EQDIRECT cables for EQ6 mounts need an extra ground and two supply pins - on top of the standard 3 pins.
29-05-2012, 02:26 PM
I think Dave's answer is where the problem lies. I have two 20 metre serial cables that can be used singly or joined together with a joiner and don't have any problem.
Are you trying to drive the scope in the native RS232 mode from the computer?
Are you using a USB to RS232 adapter?
Are you using ASCOM and EQMOD?
All these have different requirements when driven from a real com port or a virtual comport.
I don't think there is any problem with your cable if it works elswhere
29-05-2012, 03:27 PM
Thanks Dave & Barry,
I think its just the new shielded cable that has an internal problem.
I run my observatory scope for the last 7 years with another shielded cable (same type) from scope Stuff and it connects to pc through Keyspan to SkyX on laptop with no issues. This observatory cable connects to my portable LX200 no problem. Its the new cable that wont work with either scope and I just wanted to know if a shielded cable was necessary for a 5m length but from the replies (as I had suspected but wasn't sure) I am happy to make a new cable up myself from standard telephone cable.
30-05-2012, 08:49 AM
OK so now I am really baffled.
Just to recap.
1. I have 2x 25foot shielded leads (bought from Scope Stuff) - both are identical, I checked with multimeter & pins 2,3,5 on D9 connector are wired correctly to the RJ12 that plugs into the LX200R. No other pins are connected.
2. The cables are connected to my laptop (Toshiba i7 64bit) by means of a Keyspan USA 19h adaptor. This allows the telescopes to talk to the Sky X pro.
3. Cable “A” that I have had working for years in the observatory connects the LX200R and also my new LX200ACF with the SKY X through Com port 6 with no problems. I can see Keyspan in Device Manager on Com 6.
4. When I change cable and connect Cable “B” then try to connect through SkyX it returns the message “unable to detect device error 203” on both my LX200s..
This simply does not make sense to me as the cable are identically wired – a very a simple 3 wire set. How can the SkyX, or Keyspan seem to know I have changed cables?
There is no cross connection of pin outs either. I cannot see how the laptop can recognise a difference in cable either,
So last night I made a cable from telephone 4 core wire with exactly same connections as per the cable that continues to work – and when I changed the cables over and tried connecting the scope through the SkyX I get the same error message?
I will also puit this on the SkyX feedback site and see if SkyX is the problem (can't see how though).
I have considered an unlikely chance that one of the pins in the LX200 is not making contact with the RJ12 plug but surely not in 2 cables I have tried.
30-05-2012, 09:21 AM
Sorry for the obvious questions but...
* are you using the same Keyspan adapter with both cables? (I think you are?)
* how long is your newly wired cable?
* have you checked the resistance/impedance for both cable A and B?
* have you checked inside the connector itself of the working cable for cross connections?
From what you describe, my first Occam's Razor thought would be that the Cable B is damaged, and the new cable isn't wired correctly... I've personally experienced Cat5 cables that superficially appeared fine but would cause intermittent corruption - Rs232 is usually more resilient though.
To do further diagnostics I'd suggest:
* run a serial port logger/debugger on your computer to see if the bytes being sent/received are different with different cables
* hook up an oscilloscope on the RX and TX pins to see whether there's an electrical difference between the cables, e.g. too much impedance or cross talk may give you poorly shaped square waves
Well, that's all I can think of right now. What a puzzler!
30-05-2012, 11:44 AM
Yeah using same Keyspan.
Both cables are about 6 metres.
Haven't checked resistance for both cables.
The D9 connector end is a sealed unit.
Will have another play tonight and recheck the cable I made up though I am certain it is wired ok.
30-05-2012, 12:29 PM
Have you tried to connect using my PEC editor???
If not, can you try it and then save the log file,
My app will test all 255 possible ports at all possible bauds etc to see if it can connect. Just interested in what the system "sees"
30-05-2012, 01:35 PM
Yep - it would be useful to figure out whether this is a software (i.e. a serial connection is established, but there's something in the data stream that it doesn't like) or hardware (i.e. can't establish a connection at all).
Portmon is a tool that you can use to see what's going on at the interface between the software/operating system and the serial port.
You can use it to see the stream of bytes being sent/received by the computer, i.e. you'll be able to tell whether Sky X is actually sending/receiving the handshaking bytes from the LX200, or whether it can't connect at all.
30-05-2012, 01:51 PM
You say you have checked to see that 2,3 and 5 are connected through OK. I take you have you checked to see the these are not shorted together as well ie 2 goes to 2 as well as 3?
30-05-2012, 02:14 PM
Andrew I will check your pec editor tonight I found 184.108.40.206 is that the latest?
Dave will also try your link.
Hi Trevor, yeah have checked and double checked that not shorting together infact on the cable I made up I used heat shrink over each connection to the 3 pins.
30-05-2012, 04:29 PM
Portmon is an excellent tool, but it only works on the currently selected ports.
You still need to parse all the ports at selected bauds etc to test for a scope/adapter.
Once the correct port is detected,
if it still wont connect properly,
Portmon can then be used to really burrow into its guts to see whats happening,
Nope, there is a beta 4.2 at the bottom of my homepage,
( and a new one in the works for the LX800s etc )
but 3.7 will definitely do the basic "parse all ports" test looking for a scope.
30-05-2012, 04:58 PM
I used to test comms cables by this method.
This may not work with USB convertors though.
In Xp goto AllPrograms\accessories\comminicati ons and load up Hyperterminal.
Once you told it which comms port you are using you should be able to short pins 2 and 3 (Tx/Rx) together and get an echo back to hyperterm, when you are typing.
Further thoughts -- If you find the original cable works but your new one doesn't, then you need to create a null modem cable.
On the DB9 connector
connect pins 7 and 8 together ( RTS to CTS)
and connect pins 1,4, and 6 together (DCD, DTR and DSR)
Try 7 and 8 together first, you may get lucky.
Hope this helps
30-05-2012, 07:56 PM
I have found the issue and resolved it.
First thanks to all who responded it is sincerely appreciated and the level of assistance and expertise here is something Ice In Space can be proud of, a great community.
Thinking about this during the day I decided to cut the RJ12 end off the cable B and replace it with another. I wasn't confident about doing this as the cable is round and not flat. But I had suspicions there may have been a bad connection at this point. Also I noticed the Scope Stuff cables (cable A&B) have been sealed at the RJ12 end with a glue like substance, maybe this caused a bad connection I dunno.
So snip and 3 attempts and 3 RJ12 plugs later I had a connection. Tested with multimeter and plugged into LX200 & Keyspan, Turned on SkyX hit connect and you beauty connected!
As far as the cable I made last night I don't know but I will not tempt fate as I have 2 working cables.
Again thank you all.
31-05-2012, 09:27 AM
Glad to hear you finally have it all sorted :thumbsup:
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