Mitsubishi Electronics QJ71C24/-R2, QJ71C24N, SH-080007 manual 275

10 TROUBLESHOOTING

10.2.2 A compatible 1C frame communications error code table

MELSEC-Q

The following table lists the error code, error contents, and corrective action for errors generated during A compatible 1C frame communications.

Error code										Protocol
	Error				Signal					Non
(Hexa-			Error Contents					Corrective action			Bidire-
					name				MC	Proce-
decimal)											ctional
										dure
		•	A write command was designated when "Disable				• Change the setting to "Enable
								write during RUN" and restart
	Disable during		write during RUN" was set.
00H					C/N			data communications.
	RUN	•	Parameter or sequence program was written during
							• Stop the CPU and restart data
			RUN.
								communications.
01H	Parity error	•	The data does not match the parity bit setting.			P/S	• Match the Q series C24 and
								external device settings.
02H	Sum check error	•	The sum check calculated by the Q series C24 and			P/S	•	Check the external device sum
			the transmitted sum check are not the same.					check.
		•	Received message that is different from the control				• Check and correct the external
03H	Protocol error				PRO			device transmit message and
			procedure with the communication protocol setting.
								restart data communications.
04H	Framing error	•	The data does not match the stop bit setting.		SIO		• Match the Q series C24 and
								external device settings.
05H	Overrun error	•	The next data was received before the Q series C24		SIO		•	Decrease the transmission rate
			received all the preceding data.					and restart data communications.
		• Designation method error in part of a message.
	Character area	• A command that does not exist was designated.					•	Check and correct the external
06H		•	The number of processing points is outside the		PRO
	error		range for the command.					device transmit message and
								restart data transmission.
		•	A device that does not exist was designated.
07H	Character error	•	Received data that cannot be used.		PRO
		•	The CPU cannot communicate with the Q series				• Replace the CPU with a CPU that
08H	PLC access error				C/N			can communicate with the Q
			C24.
								series C24.
		•	The PLC No. is not "FF", or a station No. set in the				• Check and correct the external
10H	PLC No. error				C/N			device transmit message and
			network parameters.
								restart data communications.
		•	An error was detected upon access to the PLC				•	Send again.
11H	Mode error					—	•	Conduct individual station recovery
			CPU.
								test and check the Q series C24.
	Special function	•	A special function module does not exist at the				• Check and correct the external
12H	module designation				C/N			device transmit message and
	error		specified position.					restart data communications.
							• Check the error and take
21H	Special function	•	An error was detected upon access to a special		C/N			corrective action according to the
	module bus error		function module at the specified position.					manual of the corresponding
								module.
42H	Other errors		See	POINT		.

POINT

•If an error occurs during A compatible 1C frame communications, the Q series C24 adds a 2-character error code (00H to 10H, 42H) to the "NAK" code and returns the "NAK" code to the external device and stores the error code (equivalent to QnA compatible 2C/3C/4C frame error code) to buffer memory address 25AH (CH1) or 26AH (CH2).

The exact error contents can be checked by reading the value stored to the buffer memory.

See Section 10.2.1 for a detailed description of the error codes.

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