6014 board problems with counter 0

Hi all,

I'm working on a project with a 6014 board and Real-Time Windows Target of Matlab. I need to interface the signals from two incremental encoders. The qudrature signals are converted into a direction signal and a pulse train signal with the idea to feed them to the counters of the board, configured as bidirectional counters in up/down mode. The connections are as follows:

For Counter 0 - the pulse train signal is fed to PFI8, and the direction signal to DIO6.

For Counter 1 - pulse train signal to PFI3, direction signal to DIO7.

The problem is that Counter 1 is working properly, while with the same signals fed to Counter 0 what I read makes no sense. The counter increments by very large values at once and behaves erraticaly.

I'm seeing this behavior on two different boards.

Any help please!

Thanks in advance!

Stanislav