Endress+Hauser iTEMP TMT85, Руководство по эксплуатации

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iTEMP TMT85 System integration
Hauser 29
7.1.4 Device ID, addressing
Each fieldbus device in the FF network is identified by a unique device ID (DEVICE_ID).
The fieldbus host system (LAS) automatically gives the network address to the field device.
The network address is the address that the fieldbus currently uses.
The FOUNDATION Fieldbus
TM uses addresses between 0 and 255:
• Groups/DLL: 0 to 15
• Devices in operation: 20 to 35
• Reserve devices: 232 to 247
• Offline/substitute devices: 248 to 251
The field device tag name (PD_TAG) is assigned to the device during commissioning
(→  33). The tag name remains stored in the device even in the event of a supply
voltage failure.
7.1.5 Function blocks
The FOUNDATION Fieldbus TM 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 that a device can perform in the overall
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 blocks are available for control tasks:
• PD controller or
• PID controller
For more information, please refer to Section 13 ff.
7.1.6 Fieldbus-based process control
With FOUNDATION Fieldbus TM , field devices can perform simple process control functions
themselves and thereby reduce the workload on the superior process control system. Here,
the Link Active Scheduler (LAS) coordinates data exchange between the sensor and
controller and ensures that two field devices cannot access the bus simultaneously. For this
purpose, configuration software, e.g. NI-FBUS Configurator from National Instruments, is
used to connect the various function blocks to the desired control strategy (generally
graphically), (→  33).
7.1.7 Device description
For commissioning, diagnostics and parameter configuration, it is important to ensure that
process control systems or superior configuration systems can access all measuring device
data and have a uniform operating structure.
The device-specific information required for this is stored as so-called device description
data in special files (the 'Device Description'- DD). This makes it possible to interpret the
device data and display the data via the configuration program. The DD is therefore a kind
of “device driver”.
On the other hand, a CFF file (CFF = Common File Format) is required for network
configuration in the OFF-line mode.
These files can be acquired as follows: