Alignment does not alter the home or park position as the driver uses hard coded park positions which is not affected by any alignment/sync data. This applies to all the park positions including user defined park positions.
When you park it is to a fixed position in the sky not an object (even though the object is at that location). Even if you park and unpark within a short period of time, you would find that the object will have moved from the park position that you defined. A Goto should find the object fairly accurately unless a significant time has passed and the object is no longer within the area of sky that you have “calibrated”.
If you have a mount setup with invalid park data, you can get a fresh start by the following procedure:
(You will know that you have invalid RA/DEC park ring counter values if you execute a “Park to Home” and mount does not end up at the home position)
The above steps will reset park settings of EQMOD.
As long as the mount is still powered, you can re-connect EQMOD and the ring counter data will remain intact. The ring counters are being maintained by the stepper board. You will lose the ring counter data only if you remove power from the mount without parking it.
There are two stop buttons on the EQASCOM user interface.
The stop button one in the centre of the slew pad is an “emergency stop” and will park the mount mount at the current position. This prevents the client that initiated the slew from re-issuing slew should it detect it hasn't completed (or indeed other clients from issuing other movements). Most ASCOM client applications will not automatically unpark and so using the emergency stop will require user intervention (i.e. unpark) before and further movement is possible.
The Stop button in the tracking section will not only stop the mount tracking but will also halt slews (without the park).
Both EQMOD and HC use the same method of parking.
In HC mode, the mount initializes the ring counter values and assumes the home position (the same position manually pointed by the user to NCP upon power up). EQMOD also uses the same position as the home position. User also has to manually point the mount to the home position which is also NCP. The only condition for the usage to be interchangeable (EQMOD vs HC) is to position the worm gear to the same spot where it was found at power up prior to shutting down and this is through the park to home position found both on the HC and the EQMOD driver.
However, if you use EQMOD's user-defined park position (the HC doesn't have this feature in some versions), and then attempt to use the HC after, user will have to disengage the clutch and manually point by hand the mount back to the home position. This disengaging the clutch alone will invalidate any alignment/PEC data on the EQMOD side.
In short, to be able to use both method (HC and EQMOD) interchangeably and at the same time preserve the alignment data, you need to use only the park-to-home feature and not EQMOD's custom park-to-user-define-position.
You can use EQMOD's custom park-to-user-define-position only if you use EQMOD entirely for all mount operations.
A Synchronous Park is how the ASCOM “standard” requires that parking should be performed. The client application issues a park command to the driver which only returns control back to the client once the park has completed. For some reason ASCOM lacks an Asynchronous parking method although oddly enough it does provide both synchronous and asynchronous methods for gotos.
An asynchronous park provides a better overall control implementation as control is returned immediately to the client whilst parking is performed. This allows the client to be able to monitor and if needs be, interrupt the mount whilst parking is in progress. Traditionally EQASCOM has therefore implemented parks as asynchronous operations and this does not appear to cause issues with most clients. However, you can force synchronous behavior via the setup screen checkbox if you believe a particular client requires it.
Alignment will only be preserved between sessions if you save it and then load it again. There are options to do this manually or automatically on park/unpark.