PFI15 on BNC-2110

Dear NI community

I use a NI PCIe-6321 with a NI BNC-2110 with Labview on Windows 11.

I want to use the four counter ouputs of the 6321 to produce trains of pulses.

My problem is that the fourth counter output is on PFI15, and the BNC-2110 don't have a PFI15.

Does anyone knows how I can have access to PFI15 with the BNC-2110 ?

Thank you in advance.