Hi Gaurav,
Normally, you can update Qxxxx fields in infotypes with a code like this:
data:fieldname(25) type c value '(MP200000)Q2000'.
field-symbols: <fs> type Q2000.
ASSIGN (fieldname) TO <fs>.
MOVE '5' to <fs>-ANZHL.
Unless, in your case, the system will change the value in the ZXPADU02 but will then overwrite your value in program MP200040 FORM display
FORM display USING di_abrtg di_abrst di_ktart di_zeinh.
IF di_zeinh EQ hours.
MOVE di_abrst TO q2000-anzhl.
* else.
ELSEIF di_zeinh EQ days.
MOVE di_abrtg TO q2000-anzhl.
ELSE.
CLEAR q2000-anzhl.
ENDIF.
I am not a Time expert but I don't think it's a good idea to change this value in the user exit infotype.
It's a calculated field and you can maybee solve your problem in Time configuration.