Errors, Exception Codes - Emotron MSF 2.0 Instruction Manual

St Conel Street Nudgee SPS SP043 Electrical Switchboard Operation and Maintenance Manual (Whelan)
See section 4.7, page 42 for all parameters change-able with this function code.
2.4
Two kinds of errors are possible:
• Transmission errors.
• Operation errors.
2.4.1
Transmission errors are:
• Frame error (stop bit error).
• Parity error (if parity is used).
• CRC error.
• No message at all.
These errors are caused by i.e. electrical interference from machinery or damage
to the communication channel (cables, contact, I/O ports etc.). This unit will
not act on or answer the master when a transmission error occurs. (Same result
as if a non-existing slave is addressed). The master will eventually cause a time-
out condition.
2.4.2
If no transmission error is detected in the master query, the message is exam-
ined. If an illegal function code, data address or data value is detected, the mes-
sage is not acted upon but an answer with an exception code is sent back to the
master. This unit can also send back an exception code when a set (force) func-
tion message is received during some busy operation states.
Bit 8 (most significant bit) in the function code byte is set to a '1' in the excep-
tion response message. Example with an illegal data address when reading an
input register.
22
Q-Pulse Id TMS484

Errors, exception codes

Transmission errors
Operation errors
Modbus RTU
Active 03/12/2013
Emotron AB 01-3853-01r1
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