Prosoft-technology MVI56E-MCMR Uživatelský manuál stáhnout pdf (Strana 175)

MVI56E-MCMR ♦ ControlLogix Platform Reference

Modbus Communication Module with Reduced Data Block User Manual

ProSoft Technology, Inc. Page 175 of 225

May 13, 2014

6.4.5 RS-422

The RS-422 interface requires a single four or five wire cable. The Common

connection is optional, depending on the RS-422 network devices used. The

cable required for this interface is shown below:

6.4.6 RS-485 Application Port(s)

The RS-485 interface requires a single two or three wire cable. The Common

connection is optional, depending on the RS-485 network devices used. The

cable required for this interface is shown below:

Note: Terminating resistors are generally not required on the RS-485 network, unless you are

experiencing communication problems that can be attributed to signal echoes or reflections. In

these cases, installing a 120-ohm terminating resistor between pins 1 and 8 on the module

connector end of the RS-485 line may improve communication quality.

RS-485 and RS-422 Tip

If communication in the RS-422 or RS-485 mode does not work at first, despite

all attempts, try switching termination polarities. Some manufacturers interpret +

and -, or A and B, polarities differently.

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Prosoft-technology MVI56E-MCMR Uživatelský manuál Strana 175