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Process data and Diagnostic Status
5.4.2 I/O Messaging Connections
The transfer or exchange of process data between the scanner and the I/O device is made via a „Polled I/O Connection“, „Change of State/Cyclic“ or „Bit Strobe“.
Polled I/O Connection |
Slaves are cyclically polled by the master. |
Strobe Function |
All slaves are polled by the master by means of |
|
a command. |
Change of State |
Messages are transmitted either cyclically by |
|
the master or the slave, or in the event of a state |
|
change. |
5.5 Process data and Diagnostic Status
The data is transmitted between master and slave in the form of objects, a differentiation being made between input and output objects. The object architecture is defined by assembly objects which serve to group attributes of differing application objects. I/O data of different objects can, for this reason, be grouped to form a data block and transmitted by a message connection.
5.5.1 Process Image
The process image is differentiated according to input and output process images. The assembly object makes a statically configured process image available in the instances 1 ... 9.
The desired process image can be selected by setting the Produced Connection Path and the Consumed Connection Path of the individual I/O connections (Poll, Bit Strobe, Change of State or Change of Value).
The architecture of the individual instances of the assembly object is described in the following.
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Process data and Diagnostic Status
5.5.1.1 Assembly Instances
Permanently pre-programmed (static) assemblies in the device permit an easy and rapid transmission of input and output images from the fieldbus Coupler/Controller to the master. For this purpose, various assembly instances are provided in the fieldbus Coupler/Controller:
Output 1 (I/O Assembly Instance 1):
The entire output data image is transmitted from the master to the Controller via the corresponding I/O message connection. In this case, the data length corresponds to the number of output data in bytes. Analog output data come before digital output data.
Output 2 (I/O Assembly Instance 2):
The digital output data image is transmitted from the master to the Controller via the corresponding I/O message connection. The data length is equivalent to the number of digital output data and is rounded up to full bytes.
Output 3 (I/O Assembly Instance 3):
The analog output data image is transmitted from the master to the Controller via the corresponding I/O message connection. The data length is equivalent to the number of analog output data in bytes.
Input 1 (I/O Assembly Instance 4):
The entire input data image and one status byte are transmitted to the master via the corresponding I/O message connection. The data length is equivalent to the number of input data in bytes and one status byte.
Input 2 (I/O Assembly Instance 5):
The digital input data image and one status byte are transmitted to the master via the corresponding I/O message connection. The data length is equivalent to the number of digital input data and rounded up to full bytes. In addition, a status byte is inserted.
Input 3 (I/O Assembly Instance 6):
The analog input data image and one status byte are transmitted to the master via the corresponding I/O message connection. The data length is equivalent to the number of analog input data in bytes and one status byte.
Input 1 (I/O Assembly Instance 7):
The entire input data image is transmitted to the master via the corresponding I/O message connection. The data length is equivalent to the number of input data in byte.
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