Yokogawa Data Acquisition with PID Control CX2000 - Manual (Page 105)

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IM 04L31A01-17E
4
Modbus Protocol
4.4 Checking the Operation Status of the Modbus
Master Function
Explanation
”MODBUS STATUS” Display
You can check the operation status of the Modbus master function on the “MODBUS
STATUS” screen.
CX2000 screen example
Address and register
number of the slave
device Communication input
channel Detail code
Status lamp
Communication condition
Communication Status
The communication status is displayed using the status lamp and the detail code.
Status Lamp Detail Code Meaning
Green GOOD Communication is operating normally.
Yellow Retrying.
Red Communications stopped since communications did not recover
after the specified number of retrials.
NONE No response from the slave device.
FUNC The slave device cannot execute the command from the CX.
REGI The slave device does not have the specified register.
ERR There is an error in the response data from the slave device.
(Space) The detail code is not displayed until the status is confirmed
when communication is started.
Resuming Command Transmission
You can use the front panel keys to resume command transmission to the slave
device to which command transmission is stopped.
Data during Retrial and When Communication Is Stopped
The communication input data is held at the previous value during retrial. When
command transmission is stopped, communication input data becomes error data. In
this case, computation channels display “+******.”
Data Dropout
Data drop occurs when the commands from 1 to 8 do not complete within the read
cycle (see appendix 5). When a data dropout occurs, the communication input data is
held at the previous value. Take measures such as making the read cycle longer or
reducing the number of commands.