Burkert Type 8741 - Manual (Page 29)

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Operationandfunction
Type 8741
OPEN LOOP CONTROL function:
This function allows the duty cycle to the proportional valve to be
specified directly. When this function is activated the current duty
cycle is used.
Following a restart of the device, the cycle is set to zero.
SYSTEM ANALYSIS function:
When executing the
SYSTEM ANALYSIS function, the device operates
under the normal conditions of the AUTOMATIC operating mode.
This involves a predefined chronological sequence with setpoints.
The resulting diagram can be used in combination with the graphical
representation of process values to analyse the system via the "Bürkert
Communicator" software.
9.6.4 User-defined calibration
The devices are always delivered with a calibration by the manufacturer.
Using the "Bürkert Communicator" software, a user-defined calibration
can be specified on the basis of this calibration. For this purpose, up
to 32 calibration points can be specified.
The procedure for user-defined calibration is described in the
supplementary operating instructions "Digital Communication,
Type 8741".
9.6.5 Updating the cyclic data
The cyclic data can be updated from the device with a specific inhibit
time. The inhibit time determines the time span in which a process
value is updated.
An inhibit time of 100 ms means:
After a period of 100 ms, a new process value is provided via the
fieldbus.
For fast processes, the inhibit time for cyclic data can be reduced to
as low as 10 ms.
After a restart of the device, the inhibit time is reset to the standard time.
For field bus networks with a high number of peers, a low
inhibit time may restrict the transfer of the data from all peers.
It is recommended that the default inhibit time values of the
device are always used.
The inhibit time is changed via
• a setting in the "Bürkert Communicator" software (see section
"12.3 Bürkert Communicator (PC software)") or
• by changing an EDS object of the device.
The procedure for specifying the inhibit time is described in the
supplementary operating instructions "Digital Communication,
Type 8741".
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