
6. CONNECTION OF I/O UNITS TO
MACHINE INTERFACE
B–63783EN/01
178
Input signals for the connection unit conform to a non–insulation type
interface. There are two input types: Direct current input signal A and
direct current input signal B.
(1) Direct current input signal A
Direct current input signal A is a signal sent to the CNC from the
machine, e.g., from a button, limit switch, relay contact, or proximity
switch.
(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 (a) shows the receiver circuit for the signal.
CNCMachine
Receiver circuit
Direct
current input
signal
+24 V
Filter and level
convention circuit
Receiver
output
signal
R
Logical 0 when the
contact is open
Logical 1 when the
contact is closed
Fig. 6.8.2 (a) Receiver circuit
Fig. 6.8.2 (b) shows the time specifications for the signal.
5 to 22 ms
Direct current
input signal closed
Receiver output signal
Logical 1
(18 V or more)
Chattering of 5 ms or less is ignored
(Signal) (Signal)
5 to 22 ms
Logical 0
(6 V or less)
Open
Sink type connection (24 V common)
The high level of the direct current input signal is assigned to logic input value 1,
and the low level of the signal is assigned to logic input value 0.
Fig. 6.8.2 (b) Width and delay time of the input signal
6.8.2
Input Signal
Regulations for the
Connection Unit