
12. MAINTENANCE B-63322EN-1/01
-74-
12.2
MATERIAL FOR REMOTE BUFFER TROUBLESHOOTING
NOTE
For an explanation of the logical slot number of the R.B.
(remote buffer) board, see "Determining the Logical Slot
Number of the Remote Buffer Board," below.
No. External phenomenon Investigation method
1 Operation does not start even after a cycle start.
It is assumed that the following parameters
are set correctly:
• Baud rate
RS422: parameter 5073
RS232C: parameter 5083
• Number of stop bits
RS422: parameter 5072
RS232C: parameter 5082
• Protocol type
RS422: parameter 5074
RS232C: parameter 5084
• External synchronization baud rate
RS422: parameter 5070
• I/O device specification number
RS422: parameter 5071
RS232C: parameter 5081
Follow the procedure described below:
1 Check if the LED indication is No. 4, described under
"Normal state" in Section 1.1. If it is not, see the
"Explanation of LED Indications."
2 Perform address searches for the following addresses on
the memory display screen to check the contents of the
buffer (with "long" specified for the read/write pointers and
"byte" specified for the buffer).
n: logical slot number of the R.B. board (Note 1)
4n810500(long) : read pointer
4n810504(long) : write pointer
4n810508(Byte)
: : buffer (8Kbyte)
4n812507(Byte)
• If the read pointer is equal to the write pointer, the
buffer is empty and the cause of the error is in the
remote buffer or in the host.
• If the read pointer is not equal to the write pointer, the
cause of the error is in the NC.
3 Perform address searches for the following addresses on
the memory display screen to check the latest send data
(256 bytes) in the remote buffer (with "long" specified for
the write pointer and "byte" specified for the send buffer).
4n823100(long) : write pointer
4n823104(Byte)
: : send buffer (256byte)
4n823203(Byte)
The address equal to 4n823104 + (write pointer - 1)
contains the latest send data.
Note) The DRAM area of the remote buffer is 4n8000000H to
4n9FFFFFH. If an attempt is made to display an
address outside this range, a system error occurs.
2 Operation stopped prior to its completion. Follow the same procedure as that described above.
The causes are the same as those described above.