HBM PMX Manuel D'emploi page 53

Electrical connection
The control inputs are available at the Digital IN 1 and IN 2 terminals, as well
as the IN 3 to IN 8 terminals. They are electrically isolated from the PMX
housing, but not from each other (see Fig. 7.11).
Important
Output behavior after switch-on:
w he digital outputs have a high resistance after switch-on and retain this
T
status, until the state changes to active. The change to active status is de-
pendent on the firmware and its set actions.
w In the active state, the externally connected voltage source (see + and
terminals ) is switched through internally with low resistance, with the aid of
an electronic switch (high side switch).
Note: The electronic switch switches the + pole of the voltage source.
w In the inactive state, the electronic switch has a high resistance. If a
defined state is expected for this situation (e.g. the electronic input of a
control), a (pull-down) termination resistor must be used to terminate the
high resistance state.
w An external reference potential (
late, must be connected for the control inputs.
Important
The PX878 I/O card has electrical isolation between the analog and digital
sections and the basic device.
A3257−2.0 en/de/fr
), to which the control input signals re-
IN
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