
7. CONNECTION TO CNC PERIPHERALS
B–63443EN/02
HARDWARE
88
b1 b2 b3 b4 b5 b6 b7 b8
1 character in the start–stop system
Start bit Information bits
(8 bits including a parity bit)
Stop bits
(2 bits)
(For bit correspondence information, see the description of the SD and
RD signals in ltem 2).
(b) Codes
The following codes are used:
i) EIA code + control codes DC1 to DC4
ii) ISO code + control codes DC1 to DC4
An I/O device must be able to identify the following control
codes output from the NC system:
Character 8 7 6 5 4 3 2 1
DC1 Start tape reader Ę ° Ę
DC2 Specify tape punch Ę ° Ę
DC3 Stop tape reader Ę Ę ° Ę Ę
DC4 Release tape
punch
Ę ° Ę
NOTE
The control codes above are commonly used regardless of
whether the EIA code or ISO code is used.
With this interface, control codes DC1 to DC4 are used. Note the
following:
(a) The NC machine can control an I/O device by sending DC1
to DC4.
(b) An I/O device can perform the operations below if it is not
ready to receive data from the NC machine.
(i) The I/O device can temporarily stop data transmission
from the NC machine by using the CS signal on the NC.
The CS signal, when turned off and sent to the NC
machine, causes the NC machine to stop data
transmission after sending a maximum of two characters
including characters currently being transmitted. When
the CS signal is turned on again, data transmission
resumes.
(ii) When control code DC3 is sent to the NC machine, the
NC machine stops data transmission after sending 10 or
less characters. Then, when control code DC1 is sent to
the NC machine, the NC machine resumes data
transmission. When an I/O device containing an
ISO/EIA converter is used, the device needs to satisfy the
specifications of Table 7.3.1.