SET HOURS TO 24
Firsttime = '18:00:00'

Chk1time = '18:03:45'
? GetTimeDiff(Firsttime,Chk1time)

PROCEDURE GetTimeDiff ( time1,time2 )

RETURN TTOC({^1900/01/01 00:00} + (EVALUATE('{^1900/01/01 '+m.time2+'}')-EVALUATE('{^1900/01/01 '+m.time1+'}')),2)

ENDPROC