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MELSEC-Q
7 DATA COMMUNICATIONS USING BIDIRECTIONAL PROTOCOL
7.1.4 How to detect reception errors
This section explains how to detect errors that may occur when receiving data from the
external device.
The following items are considered as the primary causes of errors that may occur
during data reception.
Cause of reception error Reference section
A transmission error occurred because of noise. —
A timeout occurred for the no-reception monitoring time (timer 0). Section 6.1
A timeout occurred for the transmission monitoring time (timer 2) Section 6.2
Data that could not be converted with the ASCII-BIN conversion was detected.
User's Manual
(Application)
Chapter 13
Received the data length that was too long to store in the receiving area. Section 7.1.2
Simultaneous transmissions occurred. Section 7.3
(1) Confirmation using the sequence program
(a) Detecting the occurrence of a reception error
1) The single (XE/XF) is on when the ERR LED is on.
2) The receive error code is confirmed and read in the buffer memory data
reception result storage area (address: 258
H
/268
H
).
For details on how to check the error code contents and corrective
actions, see Chapter 10.
(b) How to turn off the ERR LED and clear the error code (see Section 10.1.2)
1) To turn off only the ERR LED, write a "1" to the LED OFF request area
(addresses 0
H
/1
H
) in the buffer memory.
2) To turn off the ERR LED and clear the error code, turn ON the ERR LED
OFF request output signal (YE/YF).
(Example) To perform the ERR LED OFF and the error code clear on
the CH1 side
Read command