Pilz PSS Series Operating Manual page 23

Wiring
Example: Dual-channel, failsafe input devices, without test pulses
Features:
• Depending on the application area and its respective regulations, this
connection diagram is suitable for input devices with frequent operation
and diverse channels, up to Category 4 in accordance with EN 954-1,
provided the functionality of both input device channels is monitored in
the user program via a feasibility check (see example in the
Programming Manual).
• Depending on the application area and its respective regulations, this
connection diagram is suitable for input devices with infrequent
operation up to Category 3 in accordance with EN 954-1, provided the
functionality of both input device channels is monitored in the user
program via a feasibility check.
• The possibility of a short circuit occurring between adjacent connector
terminals cannot be eliminated. For this reason, the two identical
(homogenous) channels on an input device must not be connected to
adjacent inputs.
• If you are using input devices with different (diverse) channels, adjacent
inputs may be used. The user program will detect short circuits via the
feasibility check.
CAUTION!
A short circuit in the cable between the input device and input with the L+
line or between several inputs will not be detected. Depending on the type
of input device connected, this could create a risk to both personnel and
machinery (e.g. E-STOP). Always ensure that the unit is suitably wired to
eliminate the risk of short circuits.
5-6 Operating Manual: PSS(1) DI2O Z