User`s guide

PCI-2513 User's Guide Functional Details

Maximizing encoder accuracy

If there are 512 pulses on A, the encoder position is accurate to within 360°/512.

For a position accuracy of 360°/1024, count both rising edges on A and falling edges on A.

You get maximum accuracy when counting rising and falling edges on A and on B (since B also has 512

pulses.) This gives a position accuracy of 360°/2048.

These different modes are known as X1, X2, and X4.

Connecting the PCI-2513 to an encoder

You can use up to two encoders with each PCI-2513 in your acquisition system. Each A and B signal can be

made as a single-ended connection with respect to common ground.

Differential applications are not supported.

For single-ended applications:

 Connect signals A, B, and Z to the counter inputs on the PCI-2513.

 Connect each encoder ground to GND.

You can also connect external pull-up resistors to the PCI-2513 counter input terminal blocks by placing a pull-

up resistor between any input channel and the encoder power supply. Choose a pull-up resistor value based on

the encoder's output drive capability and the input impedance of the PCI-2513. Lower values of pull-up resistors

cause less distortion, but also cause the encoder's output driver to pull down with more current.

Connecting external pull-up resistors to the PCI-2513

For open-collector outputs, you can connect external pull-up resistors to the PCI-2513's counter input terminal

blocks. You can place a pull-up resistor between any input channel and the provided +5 V power supply.

Choose a pull-up resistor value based on the encoder's output drive capability and the input impedance of the

PCI-2513. Lower values of pull-up resistors cause less distortion but also cause the encoder's output driver to

pull down with more current.

Wiring to one encoder: Figure 13 shows the connections for one encoder to a 68-pin SCSI connector on a PCI-

2513. 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 CTR0, "B" would

be connected to CTR1.

Figure 13. Encoder connections to pins on the SCSI connector*

* Connections can instead be made to the associated screw-terminals of a connected TB-100 terminal connector

option.