Rockwell-automation 1788-EN2PAR EtherNet/IP and ControlNet to PROFIBUS Manual de usuario descargar pdf (Pagina 21)

Rockwell Automation Publication 1788-UM058B-EN-P - September 2014 21

Installation Chapter 1

Cable Type and Minimum Requirements

Per section 12.8.2 of IEC61158-2 (Physical Layer Specification), the PROFIBUS

PA cable must meet the following minimum requirements:

• Impedance at 31.25 kHz of 100

Ω ± 20%

• Maximum attenuation of 3 dB/km

• Conductor cross-sectional area of 0.8mm

(18 AWG)

• Shield coverage of at least 90%

• Maximum DC resistance of 24

Ω/km per conductor

• Maximum capacitive unbalanced to the shield of 4nF/km

Cable Color Coding

Per section 12.8.8 of IEC61158-2 (Physical Layer Specification), the color code

of the PROFIBUS PA cable must match the descriptions in the following table.

Termination Guidelines

Terminate the PA bus cable at the beginning and end of the cable. You can set the

linking device to be internally terminated. If the architecture allows it,

terminators can be placed at different locations. See Appendix B

for architectures

and their correct termination locations.

Verify that junction boxes are not terminated internally. More than two

terminators will cause the communication signal to become slewed and

attenuated, which causes the signal to become unreadable.

Per section 12.8.6 of IEC61158-2 (Physical Layer Specification), terminator

impedance is equal to a 100

Ω resistor in series with a 1μF capacitor.

Cable Strand Color

PA cable positive (+) Red

PA cable negative (-) Green

Non-IS PA cable Black

IS PA cable Blue or blue/black

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Rockwell-automation 1788-EN2PAR EtherNet/IP and ControlNet to PROFIBUS Manual de usuario Pagina 21