Beijer-electronics iX Panel T70 EN Manual de usuario descargar pdf (Pagina 37)

Additional Installation Tips

11.6 GalvanicIsolation

USB

RS232RS422/485

+24 V DC

0 V

Filter

DC/DC

galvanic isolation

VCC

0 V (GND)

DC/AC

CFL

Ethernet

Internal electronic

1.5 m

5356

The operator panel has galvanic isolation against the 24 V DC feed b ut no galvanic

isolation between the communication ports for RS232, RS422/485 and USB.

Only the Ethernet connection has galvanic isolation.

* *

***

Operator panel Modular controller Printe

PCPC

Not same ground potential

* = Internal 0 V (GND) connection

Power CPU COM COM2

RS422 RS232 USB

5357

When a PC is connected to the panel, the panel’s internal 0 V (G

ND) will be

connected to the protective ground via the PC.

A number of USB devices can have the shield connected together with the

protective ground. Here, the panel’s 0 V (GND) is connected to the protective

ground when, for example, a USB memory stick, keyboard or similar device is

plugged in.

If a number of units are con nected that have a 0 V a

nd a ground connection, and

these are connected to various grounding poin

ts, there is a substantial risk of

problems. Grounding currents go through com

munication cables, the rear plate

of the controller, and i nternally in th

e operator panel, and can cause errors.

Use external units to improve communication and achieve galvanic isolation.

Westermo has good industry-standard insu lators that are also insulated from the

24 V DC feed.

Note:

Itisveryimportanttomakesurethatthe24Vfeedintheexternalinsulationunitisnot

connectedtooneofthecommunicationoutlets. Ifitdoesnothave100%insulation

againstthe24Vfeed,disturbancesandgroundingcurrentsfromthe0Vonthe24V

sidewilldisruptcommunication.

Usingthistypeofunitsolvesoneproblembutcreatesalargerproblem! Asubstandard

installationmayworknow,butproblemsmayarisewhenotherdevicesareconnected.

BeijerElectronics, MAEN006

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Beijer-electronics iX Panel T70 EN Manual de usuario Pagina 37

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