User Manual of A90 Series Inverter
294
cannot be written. If necessary, please shut down the inverter.
Parameter
protection by
password
The current register is protected by a password.
12.4 Protocol Description
12.4.1 Definition of inter-frame and intra-frame time interval
A complete MODBUS message contains not only the necessary data units, but also the
starting and ending tags. Thus, as shown in Fig. 0-1 or Fig. 0-3, the idle level with a
transmission time of 3.5 characters or more is defined as the starting and ending tag. If
there is an idle level with a transmission time of more than 1.5 characters during message
transmission, the transmission will be deemed exceptional.
Specific starting/ending and exception intervals are related to the baud rate, as detailed
in Table 0-5. If the baud rate is 9,600bps and the sampling period is 1ms, the starting and
ending time interval is the idle level of 4ms or more (3.5×10/9600=3.64≈4), and the
exceptional data interval is the idle level in which the interval of data bits of one frame is
greater than or equal to 2ms (1.5×10/9600=1.56≈2) and less than 4m (the idle level of
normal data bits is less than or equal to 1ms).
Table 0-5 Correspondence between Time Interval and Baud Rate (t
adjust
=1ms)
Starting and
ending time
interval
T
interval
(t
adjust
)
Exception
interval
T
exception
(t
adjust
)
The idle level of 3ms or less is allowed for a
normal frame. When the idle level is 8ms or
greater, it indicates the end of a frame of data.
The idle level of 1ms or less is allowed for a
normal frame. When the idle level is 4ms or
greater, it indicates the end of a frame of data.
The idle level of less than 1ms is allowed for a
normal frame. When the idle level is 2ms or
greater, it indicates the end of a frame of data.
When an idle level of 1ms appears, it indicates
the end of a frame.
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