Chapter 12: Technical Details; Technical Details Common Between U500 Pci And Isa Cards; Encoder Signal Specifications; 1.Differential Encoders - Aerotech UNIDEX 500 Operation & Technical Manual

UNIDEX 500 and Software

CHAPTER 12: TECHNICAL DETAILS

In This Section:

• Technical Details Common between U500 PCI and ISA Cards.................. 12-1

• UNIDEX 500 ISA Technical Details ........................................................ 12-21
• UNIDEX 500 PCI Technical Details ........................................................ 12-37
12.1. Technical Details Common between U500 PCI and ISA Cards

12.1.1. Encoder Signal Specifications

The UNIDEX 500 ISA Revision C board samples the encoder signals at 20 MHz. The
UNIDEX 500 PCI board samples the encoder signals at 40 MHz. The sample frequency
is not jumper selectable. The maximum input frequency is 5 MHz (4 MHz recommended)
for the ISA card and 10 MHz (8 MHz recommended) for the PCI card. The maximum
data rate for the ISA card is 20 MHz (16 MHz recommended). The maximum data rate
for the PCI card is 40 MHz (32 MHz recommended). The minimum edge separation is
50 ns (62.5 ns recommended) for the ISA card, and 25 ns (31.25 ns) for the PCI card.
12.1.1.1. Differential Encoders
The UNIDEX 500 accepts differential RS-422 type square wave encoder signals. A
"times 4" multiplication is always performed on the encoder fundamental line count. For
example, if the encoder line count is 1,000 lines, the effective machine resolution will be
4,000 machine steps (or counts) per revolution.
The marker and quadrature signals use 26LS32 type RS-422 receivers. The sine and
cosine signals are pulled to +5 V through 10K ohm resistors. The encoders are terminated
with 180 ohm resistors.
12.1.1.2. Single Ended Encoders
Third party, single ended encoders may be used with the UNIDEX 500 by connecting a
4.7K ohm 1/4 watt resistor from the unused differential input to signal common as
illustrated below in Figure 12-1.
Version 1.3
Aerotech, Inc.
Technical Details
+5v
0v
+5v
0
12-1