User`s guide

PCI-2513 User's Guide Functional Details

The "A" signal must be connected to an even-numbered channel and the associated "B" signal must be

connected to the next higher odd-numbered channel. For example, if "A" were connected to counter 0, then "B"

would be connected to counter 1.

If the encoder stops rotating, but is vibrating (due to it being mounted to a machine), you can use the debounce

feature to eliminate false edges. Choose an appropriate debounce time and apply it to each encoder channel.

Refer to the Debounce modes section in the Functional Details chapter in this manual for additional information

regarding debounce times.

You can get the relative position and velocity from the encoder. However, during an acquisition, you cannot get

data that is relative to the Z-position until the encoder locates the Z-reference.

Note that the number of Z-reference crossings can be tabulated. If the encoder was turning in only one direction,

then the Z-reference crossings equal the number of complete revolutions. This means that the data streaming to

the PC is relative position, period = 1/velocity, and revolutions.

A typical acquisition might take six readings off of the PCI-2513 as illustrated below. The user determines the

scan rate and the number of scans to take.

Figure 14. PCI-2513 acquisition of six readings per scan

Note: Digital channels do not take up analog channel scan time.

In general, the output of each channel’s counter is latched at the beginning of each scan period (called the start-

of-scan.) Every time the PCI-2513 receives a start-of-scan signal, the counter values are latched and are

available to the PCI-2513.

The PCI-2513 clears all counter channels at the beginning of the acquisition. This means that the values

returned during scan period 1 are always zero. The values returned during scan period 2 reflect what happened

during scan period 1.

The scan period defines the timing resolution for the PCI-2513. If you need a higher timing resolution, shorten

the scan period.

Wiring for two encoders: Figure 15 shows the single-ended connections for two encoders. Differential

connections do not apply.