YSI IQ S ENSOR N ET Field bus linking - Manual (Page 23)

IQ S ENSOR N ET Field bus linking Communication with field buses
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4 Communication with field buses
The IQ S ENSOR N ET monitors the current state of each sensor operated
on the system. The sensor status documents sensor information (mea-
sured value status and status info of the sensor) and current processes
(e.g. calibration or cleaning).
The sensor status is superordinate to the measured value status.
The influence of the sensor status on the measured value is docu-
mented with the status descriptions.
For the measured value to be evaluated, e.g. by a superordinate con-
trol system such as PLC, the sensor status and measured value status
also have to be taken into account together with the measured value.
A measured value is suitable for further evaluation if both of the follow-
ing conditions are met:
4.1 Communication with Profibus, Profinet, Ethernet IP
4.1.1 Data transmission
The sensor number (Sxx) is the identification for a sensor. The sensor
number is always transmitted in the first byte of the output and input da-
ta. Thus the control system (PLC) can clearly query data of individual
sensors.
The data is transferred cyclically in two steps:

Output data of the PLC:
The superordinate control system (PLC) sends a prompt to the
IQ S
ENSOR N ET to provide data of the sensor with a certain sensor
number.
 Input data of the PLC:
The IQ S
ENSOR N ET checks whether the prompted sensor number
is available and returns the data of the sensor with the relevant sen-
sor number to the superordinate control system (PLC).
1st Sensor status MEASURE
2nd Measured value status VALID