TIO Signal Connections for Counters

The following table lists the default input terminals for various counter measurements. You can use a different PFI line for any of the input terminals. To change the PFI input for a measurement, use the NI-DAQmx channel properties/attributes.

Measurement	Ctr0	Ctr1	Ctr2	Ctr3	Ctr4	Ctr5	Ctr6	Ctr7	gpsTimestampCtr0 (NI 6608 Only)	gpsTimestampCtr1 (NI 6608 Only)
Count Edges	Edges: PFI 39 Count Direction: PFI 37	Edges: PFI 35 Count Direction: PFI 33	Edges: PFI 31 Count Direction: PFI 29	Edges: PFI 27 Count Direction: PFI 25	Edges: PFI 23 Count Direction: PFI 21	Edges: PFI 19 Count Direction: PFI 17	Edges: PFI 15 Count Direction: PFI 13	Edges: PFI 11 Count Direction: PFI 9	N/A	N/A
Pulse Width Measurement	PFI 38	PFI 34	PFI 30	PFI 26	PFI 22	PFI 18	PFI 14	PFI 10	N/A	N/A
Period/Frequency Measurement (Low Frequency with One Counter)	PFI 38	PFI 34	PFI 30	PFI 26	PFI 22	PFI 18	PFI 14	PFI 10	N/A	N/A
Period/Frequency Measurement (High Frequency with Two Counters)	PFI 39	PFI 35	PFI 31	PFI 27	PFI 23	PFI 19	PFI 15	PFI 11	N/A	N/A
Period/Frequency Measurement (Large Range with Two Counters)	PFI 39	PFI 35	PFI 31	PFI 27	PFI 23	PFI 19	PFI 15	PFI 11	N/A	N/A
Semiperiod Measurement	PFI 38	PFI 34	PFI 30	PFI 26	PFI 22	PFI 18	PFI 14	PFI 10	N/A	N/A
Two-Edge Separation Measurement	Start: PFI 37 Stop: PFI 38	Start: PFI 33 Stop: PFI 34	Start: PFI 29 Stop: PFI 30	Start: PFI 25 Stop: PFI 26	Start: PFI 21 Stop: PFI 22	Start: PFI 17 Stop: PFI 18	Start: PFI 13 Stop: PFI 14	Start: PFI 9 Stop: PFI 10	N/A	N/A
Position Measurement	A: PFI 39 B: PFI 37 Z: PFI 38	A: PFI 35 B: PFI 33 Z: PFI 34	A: PFI 31 B: PFI 29 Z: PFI 30	A: PFI 27 B: PFI 25 Z: PFI 26	A: PFI 23 B: PFI 21 Z: PFI 22	A: PFI 19 B: PFI 17 Z: PFI 18	A: PFI 15 B: PFI 13 Z: PFI 14	A: PFI 11 B: PFI 9 Z: PFI 10	N/A	N/A
GPS Timestamp Measurement	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	PFI 7 Synch. Source: PFI 7	PFI 7 Synch. Source: PFI 7

Note  The NI 6601 has only four counters (ctr0–ctr3). The entries in the previous table for cntr4, cntr5, cntr6, and cntr7 do not apply for that device.

The following table lists the output terminals for counter output. You can use a different PFI line for any of the output terminals.

Ctr0	Ctr1	Ctr2	Ctr3	Ctr4	Ctr5	Ctr6	Ctr7
PFI 36	PFI 32	PFI 28	PFI 24	PFI 20	PFI 16	PFI 12	PFI 8

Note  The NI 6601 has only four counters (ctr0–ctr3). The entries in the previous table for cntr4, cntr5, cntr6, and cntr7 do not apply for that device.

NI 6624 Issues

The eight PFI lines listed as the defaults for counter output are dedicated for output, and they are the only terminals you can use for counter output. For example, you can use PFI 8 (the default for Ctr7) as the output terminal for any counter, but you cannot use it as an input terminal.

When using counter output, if the Idle State attribute/property is low, the optocouplers on the NI 6624 will still be driving your output load. Set the Idle State attribute/property to high to prevent driving the output after your task completes.