Siemens SIMATIC RF600 Series System Manual page 103

Comment
The cables with open cable ends (6GT2891-4EH20, 6GT2891-4EH50) have an 8-pin M12
plug at one end, while the other end of the cable is "open". There are 8 color-coded single
wires there for connecting to external devices.
The product range includes additional cables of the type 6GT2891-0Fxxx (2 to 50 m) with an
M12 connector at both ends. These cables can be used as extension cables. Long cables
can be shortened if necessary.
NOTICE
Insulate unused single wires
Unused single wires must be insulated individually to prevent unwanted connections of
signal lines.
NOTICE
For long cables: Adapt the power supply and transmission speed
Note that even with long cables, the supply voltage of 24 VDC must always be guaranteed.
Note also that the transmission speed on the serial interface must, if necessary, be
reduced.
SIMATIC standard cables (e.g. 6GT2891-4FN10) have a loop resistance of 160 mOhm /
meter. This results in a voltage drop of 0.8 volts on the 24 V cable for every 10 meters of
connecting cable and with a power requirement of 500 mA. If the power requirement
increases through the use of the digital inputs/outputs, the voltage drop increases
accordingly.
SIMATIC RF600
System Manual, 11/2018, J31069-D0171-U001-A21-7618
Readers
5.2 SIMATIC RF615R
103