Parameter assignment/Addressing
10.2 Description of parameters
SIPART PS2 with PROFIBUS communication
Operating Instructions, 09/2007, A5E00127926-07
145
10.2.2
Description of parameters 6 to 53
10.2.2.1
Description of parameter 6
6.SDIR - setpoint direction
Use this parameter to set the setpoint direction. The setpoint direction is used to reverse the
direction of action of the setpoint. The setpoint direction is mainly used for single-acting
actuators with the "uP" safety position.
The factory setting is "riSE".
10.2.2.2
Description of parameters 7 and 8
7.TSUP - setpoint ramp up
and
8.TSDO - setpoint ramp down
The setpoint ramp is effective in the automatic mode and restricts the modification speed of
the effective setpoint. When switching over from the manual to the automatic mode, the
setpoint ramp is used to adjust the effective setpoint to the setpoint of the positioner.
The shock-free switchover from the manual to the automatic mode prevents excessive
increase in pressure in long pipelines.
Two actuating times are determined during the initialization process. In the "TSUP = Auto"
position, the slower of the two actuating times is used for the setpoint ramp. The "TSDO"
parameter then has no effect.
The factory setting is "0".
10.2.2.3
Description of parameter 9
9.SFCT - setpoint function
Use this parameter to linearize the non-linear valve characteristic curves. Any flow
characteristics can be simulated in case of linear valve characteristic curves. For this
purpose, see the pictures below the also-see link.
Seven valve characteristic curves are stored in the positioner and are set using the "SFCT"
parameter:
Valve characteristic curve
Setting with parameter value
Linear
Lin
Equal percentage
1:25
1-25
Equal percentage
1:33
1-33
Equal percentage
1:50
1-50
