LX90 Guide via APM 909 or Autostar

[netwolf]

Hi All,

It seems that one can guide the LX90 in two ways.

One way is to use the ST-4 compatible port on the APM 909 Module, which i am guessing would require a special cable. I assume this is the Shoestring cables I have seen discussed here. Or else directly from a A guide camera that has a St-4 output.

Second way is via the Serial port connection for the AutoStar hand controller.

I have the Airlink bluetooth adapter so I would prefer to use the 2nd method to reduce cables.

Is one better than the other?
In the 2nd method can two applications be used to talk to the Autostar, like CDC/Starrynight for goto control and PHD for guiding?

Reagrds
Fahim

[acropolite]

Shoestring have both a parallel and serial adapter for interfacing. I seem to remember guiding is always done via the APM, from what I've read, the handbox method is not as effective. If you're thinking of using the APM you should get hold of one now as they're no longer being made by Meade.

[bonox]

the input delays on the APM are virtually negligible. Using the handbox has an unusual characteristic of always seeming to lag your inputs by a 1/2 second or more.

For the second question, I don't know but I think not. The APM seems to override the normal drive commands (like what the PEC inputs are for instance) but I would guess that the serial input for the handbox might get hangups about two apps trying to drive it simultaneously. I've only tried hooking the handbox to the serial port on the computer, and parallel port guide software to the APM from the same computer - not trying two apps through one port.

edit - this just in from (http://www.users.on.net/~pbl/art_autoguiding.htm)
The parallel port and relay interface method is considerably better for guiding. Dick Seymour has reported that the serial method updates the scope position every second or so but only if [autostar handbox] resources aren't being directed elsewhere at the time, whereas the APM autoguider method updates the star position 10 or more times per second and is independent of what the scope may be thinking at the time.

[netwolf]

Thanks for the excellent feedback guys. Phill, i got a APM with my LX90 so no problem there. I can only have serial and parallel ports if i use a docking station, so i was hopping to use USB to serial adapters and a serial to ST4 cable. I am guessing the ST-4 is a standard cable and can be used for both my Losmandy (digital drive) and LX90 (APM).

Regards
Fahim

[bonox]

it doesn't matter where the signal comes from, only where it goes - ie using a serial computer port to drive an ST-4 compatible scope port is fine (ie both of your mounts). You do have to make sure however that the signal is being delivered in the same way as intended (ie is the serial stream being buffered and then passed to the ST4 port like an old style parallel port, or is it just being delivered piecemeal?).

The cables should be standard, but this implies that the ports on both ends of the cable have been wired to the same standard, as you'd expect from the shoestring parallel/serial adapters and the mounts.