Reading Time From a DB And Comparing To Set Value

Hi,

After programming Omron PLCs in only LAD for many years I am new to S7 and a simple task is not working for me..

Im currently trying to read a machine cycle time value out of a data block addressand compare to a set value (50's) (STL). So when the time in the DB=50's I then want to latch on an m coil in the network below (LAD). The time in the data block is a DINT milliseconds (i.e L#40000). The time from DB resets itself after about a minute

Network 1 (STL)

L DB1013.DBD2360
L L#50000
==I
= M4000.0

Network 2 (LAD)

M4000.0 contact (from above) to drive coil M4000.1 which latches itself on. thisis reset by a nc M4000.2


Is it because the value im looking for (50s)is being passed too quickly and not held long enough to drive the latch? Could you use positive edge detection?

Any help would be great