Mitsubishi Electric AJ71C24-S6 User Manual page 84

5. HALF-DUPLEX COMMUNICATIONS USING THE RS-232C INTERFACE
MELSEC-A
5.2
Buffer Memory Settings
The following describes the buffer settings of the AJ71C24 for doing half-
duplex communications.
(
Perform the following settings with the sequence program only when the
AJ71C24 READY signal is turned ON after the CPU is reset or when the PC
CPU is turned ON.
Section 7.2 gives setting details.
(1)
Communications setting using the RS-232C interface (Address 10FH)
Set "1" to do half-duplex communications.
(2)
Setting of prioritylnon-priority at the simultaneous transmission (Address
llOH)
When the AJ71C24 and the external device begin transmitting data
simultaneously in half-duplex communications, designate (a) continua-
tion (priority) of the send from the AJ71C24, or (b) interruption (non-
priority).
Set "0" to designate " priority "
Set "1" to "225" to designate
" non-priority ".
This set value is the send wait time (unit :10 msec), until data transmis-
sion starts, after the data send state is restarted.
When an AJ71C24 is set to
"
priority ", the AJ71C24 keeps on transmitting
data and ignoring received data. Even if data is transmitted from the
external device after the AJ71C24 has started data transmission.
r
The external device that transmits data must execute the following so that
the AJ71 C24 does not ignore received data:
I
.Transmit response messages to start communications
*Resend data when a time out error of a response message occurs
I
(3) Setting the method of resend (Address 11 1H)
When setting
"
half-duplex communications "
+"
non-priority " according
t o (1) and (2), this setting becomes valid.
AS for simultaneous transmission from the external device and the
AJ71C24, when the AJ71C24 restarts the send after interruption of the
send, designate whether the interrupted message is transmitted again
from the beginning ("resend")
or
only the remaining part is transmitted
("not resend").
Set "1" t o designate
"
resend
"
Set "0" to designate
"
not resend
".