Delta Tau 5xx-603869-xUxx Setting up Quadrature Encoders, Signal Format, Hardware Setup, Value

Brick Motion Controller Hardware Reference Manual

Setting up Quadrature Encoders

Digital quadrature encoders are the most common position sensors used with Geo Drives. Interface circuitry for these encoders comes standard on board-level Turbo PMAC controllers, UMAC axis- interface boards, Geo drives, and QMAC control boxes.

Signal Format

Quadrature encoders provide two digital signals that are a function of the position of the encoder, each nominally with 50% duty cycle, and nominally one-quarter cycle apart. This format provides four distinct states per cycle of the signal, or per line of the encoder. The phase difference of the two signals permits the decoding electronics to discern the direction of travel, which would not be possible with a single signal.

Typically, these signals are at 5V TTL/CMOS levels, whether single-ended or differential. The input circuits are powered by the main 5V supply for the controller, but they can accept up to +/-12V between the signals of each differential pair, and +/-12V between a signal and the GND voltage reference.

Differential encoder signals can enhance noise immunity by providing common-mode noise rejection. Modern design standards virtually mandate their use for industrial systems, especially in the presence of PWM power amplifiers, which generate a great deal of electromagnetic interference.

Hardware Setup

The Geo Drive accepts inputs from up to eight digital encoders and provides encoder position data to the motion processor. X1 is encoder 1 connector and X2 is encoder 2 and respectively up to X8. The differential format provides a means of using twisted pair wiring that allows for better noise immunity when wired into machinery.

Geo Drives encoder interface circuitry employs differential line receivers. The wiring diagram on the right shows an example of how to connect the Geo drive to a quadrature encoder.

Function	Pin #
CHAn+	1
CHAn-	9
CHBn+	2
CHBn-	10
CHCn+	3
CHCn-	11
ENCPWR	4
GND	12

1 CHAn+

9 CHAn-

2 CHBn+

10 CHBn-

3 CHCn+

11 CHCn-

4 ENCPWRn

12	GND
5	Shield
13
6
14
7
15
8

Encoder Decode	Value	Description
I7mn0	3	Clockwise decode
	7	Counter clockwise decode

m = 0 for axis 1-4 (n = 1-4) and m = 1 for axis 5 – 8 (n = 1-4)

24 System Wiring