Appendix 5 data dropout during modbus master, Appendix 5 – Yokogawa Data Acquisition with PID Control CX2000 User Manual
Page 267
App-8
IM 04L31A01-17E
Appendix 5 Data Dropout during Modbus Master
If the response to the previous command is not complete when the CX attempts to issue
a command to a slave device, the CX command cannot issue the command, and a data
dropout results. Take appropriate measures by referring to the following figures.
Read cycle
Data dropout
(Slaves 2 and 3)
Data dropout
(Slave 3)
Slave device 1
Slave device2
Slave device3
G
Read cycle
(Retry)
: Status lamp
: Response from the slave device
: Command from the CX
Data dropout
(Slaves 2 and 3)
Data dropout (Slaves 2 and 3)
Cut off slave 2
Slave device1
Slave device2
Slave device3
Read cycle
Timeout time
Data dropout (Slaves 2 and 3)
Slave device1
Slave device2
Slave device3
G
G
G
G
Y
Timeout time
Y
Y
Timeout time
R
1. When the response from the slave device take a long time
2. When there is no response from the slave device
3. When the slave device that does not respond is cut off (with number of retrials set to 1)
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
R
G