GE IP-QUADRATURE Four Channel Decoder

GE IP-QUADRATURE Four Channel Decoder

Product Description

IP-Quadrature provides high density, cost-effective flexible implementation of four quadrature decoder channels. Channels may also be used as general purpose counters. Four independent channels provide 24-bit resolution, programmable modes, programmable polarity, interrupt capability, differential or single-ended (RS-422 or TTL/CMOS) input, read-on-the-fly capability, and a count frequency of 0 to 10 MHz.

Key Features

 • Four quadrature decoder channels, independently programmable 

 • Any channel may also act as a general purpose counter 

 • 24-bit resolution per channel 

 • DC to 10 MHz general purpose count rates 

 • DC to 1.2 MHz quadrature count rates (higher count rate in X1 and X2 modes) 

 • Counters readable “on the fly”—24-bit output register 

 • 24-bit register for capture or match interrupt on each channel 

 • Inputs may be differential or single-ended 

 • Direct connection to most sensors 

 • Programmable TTL resistor termination 

 • Each channel has a programmable control input 

 • Control input may be used to capture exact position on the fly 

 • Each channel may be used as a general purpose up/down counter 

 • Full programmable interrupt support 

 • Programmable modes; programmable prescaler: 1X, 2X, 4X. 

 • Individually programmable polarities for Count and Control inputs 

 • All CMOS 

 • Up to 16 counter channels per VME slot

Special Order Options

Versions of IP-Quadrature may be special ordered from the factory. Normally, special orders require a minimum shipment of 25 units. Special order options include:

• Depopulating for fewer channels 

 • Special input voltage requirements 

 • Special interrupt requirements 

 • Extended temperature

 • Special testing and labeling

Theory of Operation

IP-Quadrature consists of the following functional blocks:

 • Input Circuitry 

 • Polarity and Function Selection 

 • Counters 

 • Interrupt Logic 

 • IP Interface Logic

Input Circuitry

A detail diagram of the input circuit is shown in Figure 3 on the next page. The input circuitry consists of RS-422 differential receivers (comparitors) with resistors to implement termination options. Standard input is differential RS-422, terminated with 120Ω across the input. The termination resistors are socketed and may be removed or changed by the user. The resistor designators in Figure 3 are for reference here only; they do not correspond to designators on the actual IP.

Alternatively the input may be TTL or similar logic levels. One side of the RS-422 input is biased at approximately 1.75 volts, permitting single-ended TTL, NMOS, CMOS, or opto-coupler input to be directly connected. When running in this mode, one volt of hysteresis is implemented on the receiver to reduce noise. The IP-Quadrature can be converted from RS-422 input to TTL input by removing the RS-422 terminating resistor networks from their sockets. A termination network for TTL input may be switched in electronically through software.