SJ700-2 Instruction Manual NT204DX - Hitachi America, Ltd.
SJ700-2 Instruction Manual NT204DX - Hitachi America, Ltd.
SJ700-2 Instruction Manual NT204DX - Hitachi America, Ltd.
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Chapter 4 Explanation of Functions<br />
4.4.2 Communication in Modbus-RTU mode<br />
(1) Communication protocol<br />
The communication between the inverter (slave) and external control system (master) is based on the<br />
following protocol:<br />
(1) (1)<br />
External control system<br />
Inverter<br />
(2)<br />
Waiting time (silent interval +<br />
communication wait time [C078])<br />
Time<br />
(3) Communication trip limit time (C077)<br />
(If reception timeout occurs, the inverter will<br />
operate according to the setting of the<br />
operation selection after communication<br />
error [C076].)<br />
(1): Query frame that is sent from the external control system to the inverter<br />
(2): Response frame that is sent from the inverter to the external control system<br />
(3): Communication trip limit time (C077)<br />
If the inverter cannot complete the reception of a query from the master system (external control<br />
system) within the communication trip limit time, after having sent a response to the preceding query,<br />
the inverter enters the status in which to receive the query from the beginning. Subsequently, the<br />
inverter returns no response to the master system.<br />
After reception timeout occurs, the inverter operates according to the setting of the selection of<br />
operation after communication error (C076). For details, see the table below. Monitoring of reception<br />
timeout begins when the first communication is performed after the inverter power has been turned on<br />
or the inverter has been reset. Reception timeout is monitored only when the inverter communicates<br />
with the master system.<br />
Item Function code Range of data Description<br />
00: Tripping<br />
The inverter trips (E41) after reception<br />
timeout.<br />
The inverter decelerates and stops the<br />
01: Tripping after<br />
motor, and then trips (E41) after reception<br />
stopping the motor<br />
timeout.<br />
Selection of operation<br />
after communication error<br />
Communication trip limit<br />
time setting<br />
C076<br />
02: Ignoring the errors<br />
03: Stopping the<br />
motor after<br />
free-running (FRS)<br />
04: Decelerating and<br />
stopping the motor<br />
Communication wait time C078 0. to 1000. (ms)<br />
The inverter ignores the error without tripping<br />
and alarm output.<br />
The inverter stops the motor after<br />
free-running without tripping and alarm<br />
output after reception timeout.<br />
The inverter decelerates and stops the motor<br />
without tripping and alarm output after<br />
reception timeout.<br />
C077 0.00 to 99.99 (s) Limit time to determine the reception timeout<br />
Time to wait until the inverter starts sending a<br />
response after reception of a query<br />
(excluding the silent interval)<br />
The inverter sends a response (frame (2)) always after receiving a query (frame (1)). The inverter does not<br />
actively output any frame to the external control system.<br />
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