ronht The problem is, once the Meridian Flip countdown ends and the ASIair goes into it's "Flipping" routine, the mount remains stopped in it's "Custom Position Stop" mode and does not move.
Ron, the mount executes a Meridian flip (i.e., moves) when the ASIAIR sends it a GOTO command. And the mount only moves when it thinks that the position of the target of the GOTO has moved past the Meridian.
Next time it freezes, check the Local Sidereal Time of the Mount on its hand controller. Then check the RA of the target of the GOTO command from ASIAIR. Has the RA of the target moved past the Local Sidereal Time yet? (remember that an object transits the Meridian when its RA is equal to the Local Sidereal Time -- that is how sailors used to navigate; my guess is that they still teach it at Annapolis or Colorado Springs).
If the RA of the target is still on the same side of the Meridian, the mount will still execute a GOTO, but to the same side of the pier, so you won't even notice the tiny amount of movement. You will need to wait until the target has moved to the different side of the Meridian before a GOTO command from the ASIAIR will result in a Meridian flip by the mount.
There are many possible reasons for a delayed response, ranging from the mount not being perfectly leveled in the east-west direction, to the LST on the mount and LST on ASIAIR not being in sync, or for mounts without encoders, not performing any star alignment. Remember that 1 degree of non-levelness can cause 4 minutes (time) delay before the mount moves. Spending an extra minute leveling your mount perfectly can save you many minutes waiting for a Meridian flip.
Even if you have an encoder (which I think you do), you still need to make sure the encoder is calibrated while the mount is level to the ground. Perhaps your encoder has slipped from calibration -- at least there is no harm checking it to be sure. You can do that with digital inclinometers, but best to actually use stars to calibrate the encoder. Once calibrated, the encoder should hold up for at least a couple of years before it needs to be calibrated again. Especially if you don't vibrate the mount. If you are not sure, just perform a multiple-star alignment -- that should get your mount to sync with the Meridian in the sky.
The entire choreography is this: ASIAIR stops tracking N minutes before the target (i.e., the OTA) reaches Meridian. It then waits until M minutes after the target has moved past the Meridian. The ASIAIR then executes a GOTO at that second point in time. If the Mount also thinks that the target is now on a different side of its pier, the mount will execute a Meridian flip. ASIAIR takes plates before the GOTO and after it issues a GOTO. If the plate shows that the mount has not yet done a Meridian flip (ASIAIR can tell from the camera angles of the plate solves), it will wait one minute before it repeats the GOTO and another plate solve. Rinse and repeat (I have no idea how many attempts it will make before giving up). N and M are the two parameters in the Auto Meridian Flip.
Throughout all of this, all ASIAIR does is to do plate solves and send GOTO commands blindly. It is your mount that is actually computing the Meridian flip path, and performing it.
Chen
