DZ65 Digital counter board

Connection diagram see chapter C 2.5

B-53

D Transducer-connection sockets for Channel A and B Measurement transducers generating and transmitting digital signals can be connected to these sockets such as, incremen-tal and pulse transmitters whose frequencies are to be deter-mined, whose period length is to be measured or whose pul-ses are to be counted. Both sockets have the same assign-ment.

Assignment of the transducer-connection socket:

Pin Assignment Function 1)

1 Protective earth Cable screen

2 +15V Current supply for transducer

3 –15V Current supply for transducer

4 Ground Measuring ground

5 IN2+ Counter input 2+/counter-direction input 6 IN2– Counter input 2+/counter-direction input

7 Not assigned ^no

8 IN1+ Counter input 1+

9 OUT 1 Counter-control output 1

10 +5V Current supply for transducer

11 Ground Measuring ground

12 IN3+ Counter-lock input/ reset input 13 IN3– Counter-lock input/ reset input

14 OUT2 Counter-control output 2

15 IN1– Counter input 1–

Socket housing Protective earth Cable screen 1) See interface description

D Light-emitting diodes

Function boards

DMCplus complete system Digital counter board

+2.5 Carry to channel B

Channel A

Schematic circuit diagram

Counter and control DMCplus-bus

0V

Transducer supply

B-54

The digital counter board enables pulses to be counted, period lengths or frequencies to be measured and acquired isochro-nously with the measurements resulting from the other chan-nels. There are two separate counter channels A and B. If channel A operates in the preset-counter mode, channel B can be used as carry counter. There are no switches on the board; all setups required for transducer adaptation such as operating mode, measuring range, input hysteresis and low-pass filter and counter reset are computer controlled.

Operating modes:

a) Up/down counter b) Preset counter

c) Continuous period measurement d) Frequency measurement

a) Up/down counter

This operating mode is used to count pulses from different sources, to measure displacements or angles with

incremental transmitters or to count piece numbers, machine cycles, etc.

The nominal counting range is +/– 4,000,000, however, up to a maximum value of +/– 8,000,000 counting without data loss is possible. An adjustable stepwidth (scale factor) enables the number of counter steps to be reduced or increased, for example, in order to ensure measurement output up to +/–

15,625 for binary 2-byte output during which the least significant 8 bits are not transmitted.

Function boards

DMCplus complete system Digital counter board B-55

b) Preset counter

Pulses are counted consecutively until the preset number (adjustable from 2...4,000,000) has been reached.

The preset number cannot be output as measurement due to the fact that the counter is immediately set to zero when the preset number has been reached and counting is restarted.

With down-counting, the counter reading is set from zero to the preset number minus 1 at the next counter pulse and counts back to zero. If channel B is used as carry counter, it functions like a standard up/down counter, and, each time channel A is set to zero, the counter is set one step up or down.

This mode is suitable, for example, for the measurement of the angle of rotation. Channel A is scaled to 0...360¡. Channel B measures the number of rotations.

c) Continuous period measurement

This operating mode is used to measure the time period

elapsing between two input pulses. With several pulses in one measurement period (which is determined by the selected measurement rate), the computed average is output as measurement. The selected time-measurement range is represented by 4,000,000 digits.

d) Frequency measurement

The frequency for the applied input pulses is determined. The selected frequency measuring-range is represented by 4,000,000 digits. This operating mode is only suitable, for example, for speed measurement.

Function boards

DMCplus complete system Digital counter board

B-56

D Transducer-connection sockets, interface description 1) Input signals

a) Functions

IN1+ (Pin 8) / IN1- (Pin 15): Counter input 1 IN2+ (Pin 5) / IN2- (Pin 6): Counter input 2

For connecting the second phase of a 2-phase transducer, for recognition of the counter direction or to increase the resolu-tion,

or alternatively: counter direction inputoder

for transducers with output of the directional signal to change the counter direction for counter input 1.

Logic: up-counting = IN2+ > IN2–

down-counting = IN2+ < IN2–

IN3+ (Pin 12)/ IN3- (Pin 13): counter-lock input To lock counter pulses

Logic: lock counter = IN3+> IN3 enable counter = IN3+ < IN3–

or alternatively: reset input to clear (zero) counter reading Logic: reset = IN3+> IN3–

enable = IN3+ < IN3–

Function boards

DMCplus complete system Digital counter board

2.5V

IN IN +

IN –

Transducer DZ 65 +

– B

A

50k

1k

+250mV –250mV +250mV

IN –

IN +

Low

High IN

Schematic circuit diagram

Signal flow

B-57

b) Configuration

The IN1...IN3 inputs are differential inputs with voltage levels between –15V and +15V. The switching hysteresis can be ad-justed (through software via the computer) to suppress inter-ferences and to determine the switching threshold (triggering).

This permits safe operation even with signals that are chan-ging very slowly. Furthermore, a 1st-order low-pass filter with a cutoff frequency of 20kHz can be activated to reduce all hig-her frequencies. The inputs can be connected as differential inputs or also single-ended related to ground.

Differential input

With the hysteresis adjusted to 500mV the signal present at IN+ must exceed the signal at IN– by 250mV to be recognized positive (High). Then IN+ must be 250mV lower than IN– to generate a Low signal for internal processing.

Function boards

DMCplus complete system Digital counter board

2.5V

IN IN +

IN –

Transducer

DZ 65 +

–

+5V

+2.5V

IN+

0V High

Low

Hysteresis Reference point

for switching hysteresis

IN 50k

1k

Schematic circuit diagram

Signal flow

Ground

B-58

Input signal related to ground

TTL signals (0...5V) or CMOS signals (0...15V) can be connec-ted directly to the IN+ inputs or to the IN– inputs, if the nega-tive edge is to be counted. The open-ended inputs are nected to 2.5V internally thus making superfluous other con-nections. The switching hysteresis is symmetrical to this refe-rence level.

Function boards

DMCplus complete system Digital counter board B-59