Eaton PowerXL DC1 Series - 8 Modbus RTU; General; Communications

8 Modbus RTU
8.1 General
DC1 variable frequency drive 12/13 MN04020003Z-EN www.eaton.com 135
8 Modbus RTU
8.1 General
Modbus is a centrally polled bus system in which a so-called master (PLC)
controls the entire data transfer on the bus. Internode communication
between the individual modules (slaves) is not possible.
Every single data transfer operation is initiated by the master with a request.
Only one request can be sent on the cable at a time.
Slaves are not able to initiate transfers, and are only able to respond to
requests.
Two types of dialog are possible between master and slave:
• The master sends a request to a slave and waits for a response.
• The master sends a request to all slaves and does not wait for a
response (broadcast).
8.1.1 Communications
Figure 84: Modbus network with DC1
The figure shows a typical setup with a host computer (master) and any
number (a maximum of 63 modules) of DC1 variable frequency drives
(slaves) . Each variable frequency drive has a unique address on the network.
Addresses are assigned individually
to each DC1 variable frequency drive
with the P-36 parameter and are independent of their physical connection
(position) within the network.
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For more information on Modbus, please visit: www.modbus.org
L1/L
L2/N
L3
U
V
W
1
2
3
4
5
6
7
8
9
10
11
1
①②
Host Computer
L1/L
L2/N
L3
U
V
W
1
2
3
4
5
6
7
8
9
10
11
L1/L
L2/N
L3
U
V
W
1
2
3
4
5
6
7
8
9
10
11
L1/L
L2/N
L3
U
V
W
1
2
3
4
5
6
7
8
9
10
11
2 3 63
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