Metrohm 731 Relay Box - Manual (Page 28)

3. Settings
731 Relay Box, Instructions for use 22
3.2 Inverting
For each switchable output a DIP switch is available, with which
the circuit logic can be inverted.
INVERT
DC 1
DC 2
AC 2
AC 1
OFF ON
If a DIP switch is thus switched 'INVERT ON ' (to the
right) by means of a screwdriver, the appropriate
output (DC1, DC2, AC1 or AC2) is switched on if
the output line is inactive .
The relationship remote 'active' ⇒ output 'off' is
then observed, and vice versa.
The inverting circuit can also be useful to, e.g., constantly supply
an AC output (AC1, AC2) switched on, i.e. an attached device is
continuously supplied with line voltage.
To do this, set the Remote address selector AC2 (or AC1) to a
position without function (E or F) and the corresponding INVERT
DIP switch to 'ON'.