Fuji Electric ALPHA5 Smart, User Manual

Page: 523 / 636

CHAPTER 13 RS-485 COMMUNICATIONS
Modbus RTU Communications
13-35
13
(1) Amplifier’s operation when an error is detected
An amplifier operates as follows when it has detected one of various errors while receiving a query
from the master:
If an error of type (a) or (b) is detected:
The amplifier discards the data which have been received up to that time, and returns to the
reception waiting state. No response message is returned.
It is recommended that the master monitors timeout after sending a query.
If an error of type (c) is detected:
The amplifier returns an exceptional response. It must confirm the content of the query according
to the exceptional code.
(2) Master’s operation when an error is detected (recommended)
While the master is receiving a response message from an amplifier, if it has detected one of the
various errors, it is recommended to send the same query again (retry processing) after waiting for
T2 after the reception has been complete.
4. Communication time over
Communication time over is detected if any time other than 0.00 s is set on PA2_95 (communication
time over).
If an amplifier has been in the state of waiting for receiving a message over the time specified by
PA2_95, a communication time over has occurred, and all the communication CONT signals
(CONT9-24) operated by the Modbus communications are set off.
When communication time over has occurred, the station number mode of the keypad is displayed as
follows (an example of station number 01):
・
Normal display of station number
・
Communication time over
Even if communication time over has occurred, communications can be performed as usual. When the
amplifier receives a query from the master to the self station number or a broadcast query,
communication time over is cleared, and it returns to the normal display.
If PA2_95 is set to 0.00 s, communication time over is not detected. Use this setting as needed, for
example, if the system communicates periodically and you wish to detect discontinuation of the
communications.
Query
Response
Master :
Amplifier :
PA2-95
Query
Communication time over detected
Turn CONT9 to 24 OFF
T2
Cancel
Reception waiting state
Display
Communication time over detected
(“_” is displayed at the second leftmost digit.)