PHD2 mount connecting and lodestar calibration

Hello all
I am beginning to use Sequence Generator Pro and, as a result, have installed PHD2 for guiding purposes and am experiencing a couple of issues.

I cannot connect to my PMX using the SkyX drivers in PHD2 (eg the Sky controlled telescope). I get an error report saying that my mount doesn’t support the required pulse guide interface. I have fiddled with the auto guider settings in TSX, changing to pulse guide or direct drive, all to no avail.

I can connect though using the Generic Hub (ASCOM) connection. Is this adequate?

Another issue is calibration. It doesn’t happen and the message is could not calibrate in RA because the star doesn’t move enough. Have check hardware and cables. All seem good and can still calibrate and guide in Maxin.

All drivers are up to date, I believe.

Any advice or views much appreciated.



Mark, I have the same system, PMX, TSX, PHD2 and SGP.
It does work I assure you.

What version of TSX, PHD and SGP are you using? Are you using the latest ASCOM driver written by Chris Rowland? This one is available on the SB website and not the one that historically was on the ASCOM one.

You are welcome to PM me if you want to pick my brains.

I use the same setup and to expand on Chris comments

The driver can be found here

I use direct guide in the TSX and these are my driver settings


Hi, When I try to use DirectGuide with PHD2 it says Error: Mount does not support the required Pulse Guide interface. I’m using Sky-X ASCOM driver downloaded from How are you able to get DirectGuide to work?

You probably can’t.

The message means that the driver has tried using DirectGuide and got an error from TSX. There’s nothing we can do about this.

You didn’t say what mount you are using but AFAIK DirectGuide is only for SB mounts.


withdrawn - didn’t realise that later question was from different member

I’m using a Paramount MX.

  1. Is pulse drive the only way PHD2 supports guiding with a Paramount (or any other) drive?
  2. What are the benefits of Direct Drive apart from one less cable attached to the mount?
  3. Could I just use the direct guiding in SKY-X instead and not use PHD2 and still use SGP?

Thanks! Rick

Here’s the answer to #2 from Software Bisque’s website:

Autoguiding via camera relays, autoguider cables and telescope guider ports with the Paramount ME or Paramount MX has the following disadvantages:

Requires unnecessary hardware that is prone to failure

Makes "open loop" corrections to the telescope's position (specifically, when a correction to the telescope's position is performed through camera relays, the only way to determine whether or not the position of the telescope actually changed is to acquire a photo then calculate the position of the centroid of the guide star, then compare this position with the previous position of the star on the detector).

Direct Guide eliminates the need for camera relays and often unreliable and prone to fail autoguider cables and closes the loop by issuing autoguider corrections directly to the Paramount’s control system (which guarantees either telescope motion or an error message indicating “something’s wrong because the telescope did not move”).

PHD2 uses ASCOM to communicate with SkyX. PulseGuide is the ASCOM command for guiding, so if the ASCOM driver disables PulseGuide, PHD2 has no way to guide through ASCOM.


Hi Andy, So I wonder, would it be possible to have ASCOM programmed to support Direct Guide? That’s probably not on ASCOM’s roadmap as it is proprietary to Bisque.

The ASCOM standard defines a set of commands that an application like PHD2 can use to communicate with a mount. One of those standard commands is the command used to send a guide pulse, and the command is often referred to as PulseGuide. For example PHD2 may send the pulse guide command “Guide North for 20 milliseconds” to the ASCOM driver. If the ASCOM driver cannot do that, then PHD2 has no way to guide using that ASCOM driver.

Once it accepts a PulseGuide command from an application like PHD2, it is up to the ASCOM driver (in your case the “SkyX controlled telescope” ASCOM driver) to communicate with the mount in the mount’s vendor-specific command protocol.

All we can say from the PHD2 perspective is that the ASCOM driver must support the ASCOM PulseGuide command; if not, PHD2 has no way to guide.

I don’t know much at all about SkyX, so whether or not the ASCOM driver can internally support DirectGuide (and I do not even know what DirectGuide is) would be a question for the driver developer.


This is done with the current TheSky ASCOM driver.

The driver accepts ASCOM PuseGuilde commands and translates them to the SB DirectGuide commands.


I have tried all three techniques Pulse, Direct and ST4 with my PMX. Performance-wise, there is nothing to distinguish them, in so much that I could not tell by the guiding graph in PHD2.

I normally use direct guide - which as others have said, is via communication to the mount. I have had a few communication hangs however, typically when I’m imaging / guiding and at the same time do something with the TSX planetarium which requires a mount communication. I lose guiding as a result and ruin the sub, as I have to reboot the mount. So whilst cables can be unreliable, so too can the complexities of software . Swings and roundabouts.