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
-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
****ELSCRLRC
BitValueSignalFunction
0RC=1READ
COUNTER
1RL=1READ
LATCH
2SC=1SET
COUNTER
3EL=1ENABLE
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.
Rem.:The READ, SET and ENABLE commands can be transmitted in any form.
Counter status byte
After an II/O-Lightbus read operation the counter status of the M3120 points to the module in
the data byte DO. The bits of the counter command byte stand for the following functions :
76563210
STATKOMLVGF2GF1GF0EE1EE0
BitSignalFunction
0EE0Evaluation mode;
must be selectet inside the D- SUB connector by bridges to GND
1EE1*)
2GF0
3GF1
4GF2
a low pass filter is adjustable by software
the low pass filter is abjustable to 1250 kHz by hardware
5LVzero point value valid
LV = 0
The EL command was transmitted, but there was no zero impulse
yet.
LV = 1
the zero point value was latche d
6KOMCOMPLEMENTARY
shows, if a bridge is present in the D-SUB connector
KOM=0
evaluation of normal pick off signals A, B, C; bridge to GND inside
the D-SUB connector
KOM=1
additional evaluation of complementary signals; open, no bridges
inside the D-SUB connector
A, /A, B, /B, C, /C
1 = open, no bridge
inside the D-SUB connector ( 15 pins)
II/O-Setup entry
After pasting a module M3120 (incremental encoder 4 times) into the II/O-Lightbus,
following entries have to be made in the II/O-Setup.
Attention: Incremental encoder INC4 must be the fi rst entry and INC1 the fourth entry
in the II/O-Setup Table (look to the example below and to the basic circui t diagram on
page 4):
The module M3120 is connected to the fibre optic ring using fibre optic connectors (Beckhoff
Z1000). The maximum length of the FO cable, leading to the neighbouring boxes, should not
be more then 600 m for glass fibre or 45 m for other fibres. These values are only valid if for
bending the cable a radius of at least 30 mm is used. If there are no glass fibres used, no
special tools are needed for installation of the plugs.
The module M3120 is installed dezentralized from the machine. Sensors and actors are
connected to the box directly by D-SUB connectors (connector X20, X30, X40, X50).
You can take the power supply for a 5 V or 15 V incremental encoder directly from this
S-SUB connectors.
The LEDs show the status of the module.
Configuration
You can select the times of evaluation over bridges to GND inside the D-SUB connector:
EE1EE0evaluation
bridge to
GND
bridge to
GND
open,
no bridge
open,
no bridge
bridge to
GND
open,
no bridge
bridge to
GND
open,
no bridge
1 time
2 times
4 times
-
In case an encoder with single outputs is to be connected, the input "Kom" must be connected
to GND (inside the D-SUB connector X20, X30, X40, X50).
In case an encoder eith complementary outputs is to be connected, the bridge "JP" has to be
removed.
Power supply
A two pin plug in connector is used to establish the 24 V DC power supply. (X10)