Data Transfer; Device Id, Addressing; Function Blocks - Endress+Hauser PROline Prosonic Flow 93 FOUNDATION Fieldbus Operating Instructions Manual

PROline Prosonic Flow 93 FOUNDATION Fieldbus
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Endress+Hauser
Note!
Fieldbus devices such as Prosonic Flow 93, which can take over the LAS function in the
event of failure of the primary host system, are called "Link Master". This contrasts with
"simple field devices" which can receive and process data on the bus but which cannot
take over the LAS function.
5.3.3

Data transfer

We distinguish between two types of data transfer:
• Scheduled data transfer (cyclic):
All time-critical process data (i.e. continuous measurement or actuating signals) are
transferred and processed in accordance with a fixed schedule.
• Unscheduled data transfer (acyclic):
Device parameters that are not time-critical for the process and diagnosis information
are only transferred via the fieldbus when needed. This data transfer is always carried
out in the intervals between timed communication.
5.3.4

Device ID, addressing

Within the FOUNDATION Fieldbus network, each fieldbus device is identified by a
unique device ID (DEVICE_ID).
The fieldbus host system (LAS), on the other hand, automatically gives the network
address to the field device. The network address is the address that the fieldbus
currently uses.
The FOUNDATION Fieldbus uses addresses between 0 and 255:
• Groups/DLL: 0...15
• Devices in operation: 20...35
• Reserve devices: 232...247
• Offline/substitute devices: 248...251
The tag name (PD_TAG) is given to the device in question during commissioning
(see Page 66). It remains stored in the device even during a power supply failure.
5.3.5

Function blocks

The FOUNDATION Fieldbus uses predefined function blocks to describe the functions
of a device and to specify uniform data access. The function blocks implemented in
each fieldbus device provide information on the tasks which a device can accept in the
whole of the automation strategy.
In the case of sensors these are typically the following blocks:
• Analog Input or
• Discrete Input (digital input)
Actuating valves normally have the following function blocks:
• Analog Output or
• Discrete Output (digital output)
The following are examples of blocks for control tasks:
• PD controller or
• PID controller
Note!
Further information on this can be found in the separate "Description of Device
Functions" manual.
5 Operation
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