Electrical Installation - Siemens simatic hmi op7 Equipment Manual

14.2

Electrical Installation

Electrical
connections
Interference-proof
hardware design
!
Polarity reversal
protection
Equipment Manual OP7, OP17
Release 04/99
The OP requires the following electrical connections
to the power supply,
to the configuring computer (PC or programming unit),
to the PLC.
The electrical connection to the configuration computer is required only to
download the firmware and configuration.
The basis for interference-free operation is interference-proof hardware
design of the PLC in accordance with EMC guidelines and the use of
interference-proof cables. The guidelines for interference-proof design of
your PLCs also apply accordingly for installation of the OP.
Caution
Use only shielded cable for all signal connections.
Screw down or lock all plug connections.
Do not install signal lines in the same cable ducts as high voltage lines.
Siemens AG accepts no responsibility whatsoever for malfunctions and
damage arising from the use of self-made cables or cables from other
manufacturers.
The OPs have polarity reversal protection. This does not work if there is al-
ready a link to another unit via an RS232 interface. For this reason, always
proceed as follows whenever commissioning the OP:
1. Connect the power supply.
2. Switch on the OP. If the OP does not run up, swap over the connections
because their polarity is reversed.
3. Once the OP has run up, connect the configuration computer or I/O de-
vice.
14-3