User`s guide

PCI-2513 User's Guide Functional Details

Stop at the top mode

The counter stops at the top of its count. The top of the count is FFFF hex (65,535) for the 16-bit mode, and

FFFFFFFF hex (4,294,967,295) for the 32-bit mode.

32-bit or 16-bit

Sets the counter type to either 16-bits or 32-bits. The type of counter only matters if the counter is using the

stop at the top mode—otherwise, this option is ignored.

Latch on map

Sets the signal on the mapped counter input to latch the count.

By default, the start of scan signal—a signal internal to the PCI-2513 pulses once every scan period to indicate

the start of a scan group—latches the count, so the count is updated each time a scan is started.

Gating "on" mode

Sets the gating option to "on" for the mapped channel, enabling the mapped channel to gate the counter.

Any counter can be gated by the mapped channel. When the mapped channel is high, the counter is enabled.

When the mapped channel is low, the counter is disabled (but holds the count value). The mapped channel can

be any counter input channel other than the counter being gated.

Decrement "on" mode

Sets the counter decrement option to "on" for the mapped channel. The input channel for the counter increments

the counter, and you can use the mapped channel to decrement the counter.

Debounce modes

Each channel's output can be debounced with 16 programmable debounce times from 500 ns to 25.5 ms. The

debounce circuitry eliminates switch-induced transients typically associated with electro-mechanical devices

including relays, proximity switches, and encoders.

There are two debounce modes, as well as a debounce bypass, as shown in Figure 6. In addition, the signal from

the buffer can be inverted before it enters the debounce circuitry. The inverter is used to make the input rising-

edge or falling-edge sensitive.

Edge selection is available with or without debounce. In this case the debounce time setting is ignored and the

input signal goes straight from the inverter or inverter bypass to the counter module.

There are 16 different debounce times. In either debounce mode, the debounce time selected determines how

fast the signal can change and still be recognized.

The two debounce modes are trigger after stable and trigger before stable. A discussion of the two modes

follows.