Solution
For most NI DAQ devices, the counter/timer signal assignments to the PFI lines are generally the same. The primary difference is the physical connector pin number associated with each PFI line. The table below summarizes the counter terminal mappings for the USB-6451 and/or USB-6453.
| Counter/Timer Signal | Terminal Name | Default Pin Number |
| CTR 0 SRC | PFI 8 | 8 |
| CTR 0 GATE | PFI 9 | 9 |
| CTR 0 AUX | PFI 10 | 11 |
| CTR 0 OUT | PFI 12 | 14 |
| CTR 0 A | PFI 8 | 8 |
| CTR 0 Z | PFI 9 | 9 |
| CTR 0 B | PFI 10 | 11 |
| CTR 1 SRC | PFI 3 | 29 |
| CTR 1 GATE | PFI 4 | 31 |
| CTR 1 AUX | PFI 11 | 12 |
| CTR 1 OUT | PFI 13 | 15 |
| CTR 1 A | PFI 3 | 29 |
| CTR 1 Z | PFI 4 | 31 |
| CTR 1 B | PFI 11 | 12 |
| CTR 2 SRC | PFI 0 | 25 |
| CTR 2 GATE | PFI 1 | 26 |
| CTR 2 AUX | PFI 2 | 28 |
| CTR 2 OUT | PFI 14 | 17 |
| CTR 2 A | PFI 0 | 25 |
| CTR 2 Z | PFI 1 | 26 |
| CTR 2 B | PFI 2 | 28 |
| CTR 3 SRC | PFI 5 | 32 |
| CTR 3 GATE | PFI 6 | 34 |
| CTR 3 AUX | PFI 7 | 35 |
| CTR 3 OUT | PFI 15 | 18 |
| CTR 3 A | PFI 5 | 32 |
| CTR 3 Z | PFI 6 | 34 |
| CTR 3 B | PFI 7 | 35 |
| FREQ OUT | PFI 14 | 17 |