Command value input 2 is a differential input [1] (0 to + 10 V). With
the help of DIL switches
2)
it can be configured as current input (4 to
20 mA or 0 to + 20 mA). If the command value is provided by exter
nal electronics with another reference potential (e.g. from a PLC)
this input must be used. When cutting the command value voltage in
or out, care must be taken that both signal lines are disconnected
from or connected to the input.
Before being passed on, both command values are summated [2
and then fed to a potentiometer [3] which is accessible from the
front and acts as an attenuator thus limiting the maximum com-
mand value.
The ramp generator [4] connected downstream generates a ramp-
shaped output signal from a stepped input signal. The time constan
of this signal can be adjusted separately for the “up” and
“down”ramps with the help of two potentiometers. The indicated
ramp time refers to a command value step-change of 100% and can
be approx. 1 s or 5 s, depending on the setting by means of a DIL
switch
2)
. If a command value step-change smaller than 100 % is fed
to the input of the ramp generator, or the attenuator [3] is active, the
ramp time shortens accordingly.