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The standard IEC 61158-2 specifies four different types of cable for use in PROFIBUS PA with MBP segments (see table below). MBP type A cable - not the same as RS 485 type A cable – is a two-wire, screened and stranded cable with the best possible performance characteristics regarding signal  line loss and cable length.



Conductor pairs


Conductor cross-section

Max resistance per unit length

Max total cable length

Type A

A few

Yes (90%)

0.8 mm2

44 Ω/km

1900 m

Type B


Over all

0.32 mm2

112 Ω/km

1200 m

Type C



0.13 mm2

264 Ω/km

400 m

Type D



1.25 mm2

40 Ω/km

200 m


If type A cables are used, overall cable length, including stub lines, should be maximum 1.9 km. When used in potentially explosive environments and intrinsically safe construction, line lengths are greatly reduced.


It is advisable to use cable type A for new installations. However, it is also practical if other cables can be used, especially when existing systems have to be converted to PROFIBUS PA.