Vacon 100 INDUSTRIAL - Page 12

3
vacon • 10 Modbus technical data
Local contacts: http://drives.danfoss.com/danfoss-drives/local-contacts/
Figure 4. Modbus TCP and UDP communication errors comparison
Figure 5. Modbus TCP retransmissions
11717_uk
Modbus TCP Communication
PLC Drive
Modbus Query (1)
Modbus Query (2)
Modbus Response (1), TCP, ACK
Modbus Response (2), TCP, ACK
TCP, ACK
TCP retransmission, Modbus Query (2)
TCP retransmission, Modbus Query (2)
Normal communication continues
Packet lost, no response
Packet lost, no response
Modbus Query (1)
Modbus Response (1)
Modbus Response (4)
Modbus Query (2)
Modbus Query (3)
Modbus Query (4)
Packet lost, no response
Packet lost, no response
Normal communication continues
Modbus UDP Communication
PLC Drive
11718_uk
Modbus TCP Communication
PLC Drive
Modbus Modbus
TCP
stack
TCP
stack
Modbus Query (1)
Modbus Query (2)
Modbus Query (3)
Modbus Query (4)
Modbus Query
(1,2,3)
Modbus Query (4)
Modbus Response
(1,2,3)
Modbus Response
(4)
TCP Modbus Query
TCP, ACK
TCP, ACK
TCP, ACK
TCP, ACK
TCP, Modbus Response (1,2,3)
TCP, Modbus Response (4)
TCP, Modbus Query (4)
Retransmission
Modbus Query (1,2,3)
Retransmission Modbus Query (1,2,3)
Retransmission
Modbus Query (1,2)
Retransmission
Modbus Query (1)
Modbus
Response (1,2,3)
Modbus
Response (4)
Normal communication continues
Packet lost