
B–63783EN/01
6. CONNECTION OF I/O UNITS TO
MACHINE INTERFACE
179
(2) Direct current input signal B
Direct current input signal B is a signal sent from the machine to the
CNC and used at high speed.
(a) The contacts on the machine must meet the following
requirements:
Contact capacity: 30 VDC, 16 mA or more
Leakage current between contacts when the circuit is open:
1 mA or less (Voltage: 26.4 V)
Voltage drop between contacts when the circuit is closed:
2 V or less (Current: 8.5 mA)
(Including the voltage drop through the cable)
(b)Fig. 6.8.2 (c) shows the receiver circuit for the signal.
CNC
+24 V
Filter and level
conversion circuit
Receiver
output
R
Machine
Output transistor
Receiver circuit
Fig. 6.8.2 (c) Receiver circuit
As shown in Fig. 6.4.2 (c), the common voltage for the connection
unit can be selected from +24 V and 0 V by the wiring on the
machine.
(a) To use the connection unit with the +24 V common voltage
Connect
Ę
A
with
Ę
B
and
Ę
C
with
Ę
D
. Logical 0 when the
transistor is off. Logical 1 when the transistor is on.
(b)To use with the 0 V common voltage
Connect
Ę
A
with
Ę
D
and
Ę
B
with
Ę
C
. Logical 1 when the
transistor is off. Logical 0 when the transistor is on.
Fig. 6.8.2. (d) shows the time specifications for the signal.
2 ms max
ON
OFF
Receiver
output signal
Logical 1
(18 V or higher)
Logical 0
(6 V or higher)
2 ms max
(For +24 V common)
Logical 0
(6 V or lower)
Logical 1
(18 V or lower)
(For 0 V common)
Direct current
input signal
Fig. 6.8.2 (d) Width and delay time of the input signal