Siemens Simatic M7-400, Руководство по установке

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Assembling and Installing Systems
A-34
S7-400 and M7-400 Programmable Controllers Hardware and Installation
A5E00069481-04
Important Information
Even when electronic control equipment has been configured for maximum design
safety – e.g. with a multi-channel structure – it is imperative conform with
instructions given in the operating manual. Incorrect handling can render measures
intended to prevent dangerous faults ineffective, or generate additional sources of
danger.
A.12 Interference-Free Connection of Monitors
Introduction
You can use operator interfaces with monitor ports from the COROS product family.
The layout of apparatus and the interference content of the environment
significantly affect the interference-free connection of monitors to a programmable
controller. The choice of monitor and video cables is governed by whether the
monitor and programmable controller are to be operated under low-interference
conditions or under industrial conditions.
Operation under Low-Interference Conditions
Where a monitor and the programmable controller operate in a low-interference
environment and there is only a short distance between monitor and programmable
controller, they are at almost the same ground potentials. Interference and
disturbance by ground loops are therefore not expected.
In these cases, you can use either TTL or analog signals to drive the monitor.
Digital cables or single-shielded coaxial cables can be used to transmit the video
signals. Note that the braided shield of the coaxial cable serves as the return
conductor and must not be connected to the shield bus. The monitor and
communications processor (CP) are interconnected without additional shielding
and grounding.