The limit value of the Memorizing channel

The customer encountered a strange problem, they use the MEM channel to accumulate the total mileage. The system uses MD5 and MC43FS controllers, and the programs are also separate. The customer uses the same algorithm to perform operations in two separate controllers. In MD5, everything is normal and the total accumulated mileage has been increasing all the time. However, in MC43FS, once the values accumulate to 2048km, they will no longer increase. I use the IQANsimulate to monitor that MC43FS can also break through 2048km. 

The difference between the two programs lies in their different Cycle time. MD5 is 50ms, MC43FS is 10ms.

What could be the reasons for this problem?