Instruction Manual

5-12
<Toc> <Ind> <5. MODBUS Communication >
IM 77J04J11-01E 1st Edition : 2006.08.25-00
5.2.2 Response Error Codes
● Message Format in the Event of Error
If there are any inconsistencies other than communication errors in a message, the M
Series does nothing, but returns the following message.
Number of bytes in RTU mode
Number of bytes in ASCII mode 2
2
Address
Number
(ADR)
Element Function Code
(*1)
Error Code Error Check [CR] [LF]
2
None
2
1
2
1
2
1
*1: In this case, a value of [function code (hexadecimal number) + number 80 (hexadecimal number)] is set.
● Response Error Codes
Table 5-3 List of Error Codes
01
Error Code Meaning Cause
02 D-register number error
Function code error
03 D-register count error
Specified D register number is out of the range.
No such function code exists.
Specified number of D registers is out of the range.
● Even when a message is sent, no response returns if:
• Retransmission error (overrun, framing, parity, LRC, or CRC-16 error) was detected.
• Address in a command message is incorrect.
• Interval between data composing a message was 2 seconds or more.
• CRC-16 or LRC values are incorrect.
• Broadcase is specified (address number: 00).
Note: As a countermeasure, provide a timeout process in the communication functions of a higher-level device or in the
communication program.