Commissioning the System
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Publication S177E V2.0 Issue 03/05
13 COMMISSIONING THE SYSTEM
IMPORTANT SAFETY PRECAUTIONS
In order to fully commission the Pakscan Loop it is necessary to ensure that all the system's
valves are allowed to be opened and closed. Also any ancillary devices such as pumps and
stirrers must be allowed to operate. Without this capability it is impossible to check all the
functions of the total system.
It may be that valve movement and pump operation is not permissible, as the plant may
already be operational in a manual mode. In this case it will only be possible to test out parts
of the Pakscan system. However if the connected field units are to operate devices on a 'live'
plant it is vital to secure the connected equipment into a safe state. Ensure that the
connected actuators are in Local control or locked in 'Hand' (as this will prevent them from
moving under Pakscan control) and any other plant equipment connected to field units is
either able to be operated safely, or that the outputs are prevented from operating the
connected equipment.
Don’t forget that an actuator set to Local will still respond to an ESD signal and may move
the valve. It is also advisable to ensure that all the connected equipment is safe, for example
in Local Stop, whenever the loop is re-configured.
The plant should only be returned to its original state once the loop is operating correctly.
BEFORE YOU START
Ensure all the measurements and checks described I section 7.4 have been carried out.
When the loop resistance and capacitance was measured the operating loop baud rate was
determined. This baud rate must be set as the operating speed for ALL the connected field
units. Note that the 'Doubling' option described in 9.3 above is an independent function, the
cable parameters and number of field units present determine the baud rate selection.
Set all the field units to match the master station Loop Baud Rate.
13.1 Checking Individual Field Units.
Use a Paktester to verify that each and every field unit is correctly set for Baud rate and Address.
Where there are options for the setting of the field unit make sure these are adjusted correctly. Refer
to the Paktester manual (S178E) for information regarding these adjustments. All field units, including
those simply used for full open and full close duty, report analogue values for valve position.
Whenever this data is not required, the Analogue Update Time and Deviation settings should be set to
switch off this reporting, or to the maximum acceptable value. If these parameters are not correctly set
then the field unit will be sending analogue messages far to often and slow down the remaining data
communication on the loop.
Pay particular attention to selecting the correct function for General Purpose field units, and also for
the settings for Analogue Update times and Deviation settings for all field units where analogue data is
collected as mentioned above.
