Simulated Motor: Moving after setting MRES fails

[DominicOram]

When using a simulated motor the first move after setting an MRES fails. e.g. the following do not work:

• MRES -> MOVE
• MRES -> JOG

but the following (2nd move) will work:

• MRES -> MOVE -> MOVE

It appears you can also somehow get the simulated motor out of this state but I haven't worked out exactly how. I spent half a day debugging and found that adding print statements/breakpoints into the motor code would fix the problem and so continuing to debug will be hard. Given that this has only been seen on simulated motors and is a known problem I stopped digging any further.

Acceptance criteria

• Setting an MRES and then moving a simulated motor works first time

[FreddieAkeroyd]

This only fails for me if VAL/DVAL is 0 when I set MRES, is that the same for you?

[FreddieAkeroyd]

The above two PRs look to fix it on my machine, but may not in general - it does seem intermittent sometimes.