Appendix 5 data dropout during modbus master, Appendix 5 – Yokogawa Data Acquisition with PID Control CX2000 User Manual

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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

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

Timeout time

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)