Building a PROFIBUSâ DP line with FieldBusPlugs

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Note

When an AC500 CPU is used as Fieldbus master, the power supply of the CPU and those of the FieldbusPlug should be separated to provide a better interference immunity. The two power supplies should be integrated in the global earthing/grounding scheme of the installation.

Installation of the PROFIBUSâ line step by step:

  1. Connect PDA11 (Adapter Cable Dsub9-M12) to the bus master.

  2. Do not forget to set the termination switch on the PDA11 (green) to ON.

  3. Connect the red and blue strand of the PDA11 with a 24VDC power supply  (+ red, - blue).

  4. Connect the first PDP21 or PDP22 to the PDA11, then the next PDP21 or PDP22 and so on. Tighten the knurled knob carefully. The roughness felt during tightening shall result in resistance to vibration.

  5. Do not forget to mount the PDR11 (active PROFIBUSâ termination unit).

A fault-free and stable data transmission urgently requests the perfect termination of the bus line on both ends and nowhere else. This has to be regarded also when repeaters or optical converters are used.

The max.  number of stations per segment is 32 limited physically by the RS485 standard line drivers and receivers. This includes also repeaters and similar components.

For more than 32 stations repeaters or RS485-to-optical-fiber converters can be used.

Another limit is given by the max. number of 125 slave addresses. The available range is 1 through 125. More details see “Data structure, addressing PROFIBUSâ DP built with PDP21 and PDP22 FieldBusPlugs”