M Series devices have up to 16 PFI lines. Each PFI can be individually configured as the following:
- Static Digital Input
- Static Digital Output
- Timing Input Signal for AI, AO, DI, DO, or counter/timer functions
- Timing Output Signal from AI, AO, DI, DO, or counter/timer functions
Each PFI line can be individually configured as a static digital input or a static digital output. When a terminal is used as a static digital input or output, it is called P1.x or P2.x. On the I/O connector, each terminal is labeled PFI x/P1.x or PFI x/P2.x. Static I/O is basic digital I/O that employs no handshaking or hardware-controlled timing. Static I/O mode is interrupt driven, so it is relatively slow, allowing a maximum of about 10 kHz depending on your computer.
When a terminal is used as a timing input or output signal, it is called PFI x (where x is an integer from 0 to 15). When a terminal is used as a static digital input or output, it is called P1.x or P2.x. On the I/O connector, each terminal is labeled PFI x/P1.x or PFI x/P2.x. The voltage input levels, voltage output level, and current drive levels of the PFI signals are listed in the specifications of your device.
Measurement and Automation Explorer (MAX) offers Device Route tabs for M Series devices, which contains information on routes available. Additionally, you can enable a programmable debouncing filter on each PFI signal. When the filters are enabled, your device samples the input on each rising edge of a filter clock. M Series devices use an onboard oscillator to generate the filter clock with a 40 MHz frequency.