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3. PROCEDURES PRIOR TO COMPUTER LINK FUNCTION
OPERATIONS DESCRIBED IN THIS GUIDEBOOK
MELSEC-A
.I
3 . 2
Self-Loopback Test
Self-loopback test is to check the AJ71 UC24 to see if it works properly when
unconnected to the computer.
The functions for communications with the PC CPU and those of the RS-232C
or RS-422/485 interface for transmitting and receiving data are to be checked.
(Step 1) Setting the mode setting switch
(Step 2)
Setting the transmission specifications setting switches
Set the mode setting switch to "F" to select self-loopback test.
Set the transmission specifications setting switches as shown
in Section 3.1.2.
Connect the RS-232C connector cables or RS-422/485 terminal
block cables as shown below:
(Step 3) Connecting cables
I
RS232C Cable Connections
I
AJ71UC24
I
cs
DSR
6
I I
SG
i
7
1
I
~~
RS-422/465 Cablo Connections
1 7 1
Cable Connection
AJllUC24
Signal
SDA
SDB
RDA
RDB
I
SG
1
t
FG
(1) Engage a connector with the above cable connections for testing to
(2) Short the terminals of the RS-422/485 connector as shown in the
the RS-232C connector.
above figure.
(Step 4)
Carrying out a self-loopback test
1) Set the RUN/STOP key switch on the PC CPU to STOP.
2) As soon as the power to the PC CPU is turned on or the
CPU is reset, an AJ71UC24 READY signal (ready signal)
will be turned on and checking will automatically start.
(The READY signal will be turned on several seconds after
the power is turned on or the CPU is reset.)
Checking proceeds and repeats in the sequence of
(1)
PC
CPU communications check
+
(2) RS-232C check
+
(3)
RS-422/485 check.
(The AJ71 UC24 automatically executes it.)
3) Checking sequence
3 - 4
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