BECKHOFF M3120 User Manual

M3120 Incremental encoder 4x Beckhoff II/O-Lightbus

M3120

Incremental encoder

4 x

Technical description

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D-33415 Verl fax [phone]

Date 20.10.94 Version 1.1 Page 1 of 14

M3120 Incremental encoder 4x Beckhoff II/O-Lightbus

Table of vontents

1. Function description hardware ........................................................................3

2. Function description software ..........................................................................5

3. Technical data....................................................................................................8

4. Installation........................................................................................................10

5. Connection table ..............................................................................................12

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M3120 Incremental encoder 4x Beckhoff II/O-Lightbus

1. Function description hardware

M3120

The periphery module M3120 establishes the connection of four incremental encoders for the
II/O-Lightbus system. It contains three separate power supplies for logic (5V) and pick off
power supply (5/15V) and the level adjustment from 15 V down to 5V. 5 V or 15 V encoder
can be connected to the incremental box M3120, either with or without complementary
channels.

All digital functions are integrated in four separate periphery controller (LCA circuit):

- 24 bit UP/DOWN counter with a limiting frequency of 1.25 MHz.

- Input "counter disable"

- 24 bit latch for counter position at zero impulse.

- Squareness decoder with adjustable 1, 2 or 4 times evaluation

- Selective computation of complementary signals (fewer interferences)

- Connection to the II/O-Lightbus with all functions:
addressing, interrupt, address counting, decrease transmission intensity,

cycle and error LED

- Read, set and activate commands for counter and zero impulse register via fibre

optic II/O-Lightbus

Date 20.10.94 Version 1.1 Page 3 of 14

M3120 Incremental encoder 4x Beckhoff II/O-Lightbus

Basic circuit diagram

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M3120 Incremental encoder 4x Beckhoff II/O-Lightbus

2. Function description software

Counter functions

- The counter commands are sent in data byte D0 to the module M3120.

- In the data byte D0 the counter status byte is received .

- the counter command byte can only be written

- the counter status byte can only be read.

Counter command byte

In order to transmit commands to the module M3120, the following bits of the counter
command byte can be set and then written to the data byte D0 of an II/O-Lightbus telegram.

76563210

* * * * EL SC RL RC

Bit Value Signal Function

0 RC=1 READ

COUNTER

1 RL=1 READ

LATCH

2SC=1SET

COUNTER

3 EL=1 ENABLE

LATCH

Read 24 bit counter

(D1 = LOW byte, D2 = MID byte, D3 = HIGH byte)

Read 24 bit zero point latch

(D1 = LOW byte, D2 = MID byte, D3 = HIGH byte)
The zero point value (see EL command) is only valid, if the LATCH
VALID bit LV is set in the counter sta tus byte. Only a single read
command can be executed at a time. If in a command byte RC=1 and

RL=1, then no value is read

.

Set counter

The counter is only set, if 0001xxxxb is the value in the control byte
of the II/O telegram.

Activate the zero point latch

the counter is stored in a 24 bit register at the fir st zer o impulse afte r
the EL command was transmitted. Using the RL command the value
can be read many times at any tim e, The LV bit is only dele ted after
the EL command was transmitted. It is only set again, if a zero point
value was stored. The EL com mand is only executed, if 0001xxxx
is the value in the control byte of the II/O telegram.

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