2.2.2 M12-plug connections (part two)

MBP (PA) connectors

The 4-pin M12 connector is used for PROFIBUS-MBP (PA). Three of the four contacts are used. The following variant of the M-12 connector (A-coding) is used for the PROFIBUS-MBP (PA).

Fig.: 4-pin M-12 connector (for MBP (PA)
male plug (left) and female socket (right)

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Table: 4-pin M-12 connector
(for MBP (PA))

M-12 connectors are suited for use outside of control cabinets (IP 65/67). One side of the connector is permanently installed in the PROFIBUS station and the other connector is connected to the cable.

In many applications, the installation can be simplified by using preassembled PROFIBUS cables. These PROFIBUS cables are available ready-tested and in different lengths.

Tee units are available for M-12 connectors to connect PROFIBUS cable segments. For PROFIBUS-MBP (PA), the PROFIBUS stations are generally connected via tee units. For PROFIBUS-RS 485, tee units are available as options. Special Tee units containing decoupling circuits need to be used for baud rates from 3 to 12 MBaud.

Some M-12 connectors label the pins “A” and “B” or give a color reference e.g. “green” and “red”. These two pins connect to the two data wires in the PROFIBUS cable. The color scheme must be used consistently within a segment; i.e. the cores must not be swapped over. The PROFIBUS guideline Interconnection Technology specifies the following assignment:

A green

B red

Wiring techniques differ from manufacturer to manufacturer; these can be divided into two groups: preassembled PROFIBUS cables and field-assembled PROFIBUS cables. The wiring techniques for pre-assembled PROFIBUS cables require special tools. For this reason, you should always select a method that can be field-assembled for on-site installation. This also offers the benefit that the PROFIBUS cable can be easily reconnected in case of repair or maintenance.

For field assembled cables the following technologies are used:

1. Screw methods
2. Insulation displacement methods
3. Cage clamp technology
   

The following sections provide examples of a few implemented solutions from different manufacturers. However, they do not provide full assembly instructions. You should always refer to the specific manufacturer’s instructions.

The wiring techniques for the pre-assembled PROFIBUS cables require special tools. For this reason, you should always select a method that can be field-assembled for an on-site installation. This also offers the benefit that the PROFIBUS cable can be reconnected in case of repair or maintenance.

Ensure that you are only using PROFIBUS cables approved by the connector manufacturer for use with the respective connector. This applies particularly to the use of insulation displacement technology. In addition, ensure that the conductor diameter matches the connector housing for IP 65 applications. Only then is a correct seal between the connector and cable ensured

For M-12 connectors, there are several methods for establishing the bus termination. These are:

1. Use of termination connectors
2. Termination integrated in the tee unit
3. Termination integrated in the device