Digital Inputs/Outputs - Siemens SINAMICS GM150 Operating And Installation Instructions

Operation
8.4 Functions
8.4.2.3

Digital inputs/outputs

The TM15 modules are the interface with the system I/O. These modules are used to read the
signals to the closed-loop controller. The signal status is indicated by a green LED on the front
panel. The TM15 module is equipped with 24 floating digital inputs/outputs, which are divided
into three groups of eight channels. Each group has a separate supply voltage connection
[(L1+, M1), (L2+, M2), (L3+, M3)]. This enables signals to be processed with separate
reference potentials. If a system supply voltage for monitoring signals is not available, the
signal monitoring function can be supplied by the 2P24, which is protected with a circuit-
breaker. In this case, the 0 V potential of the closed-loop controller is distributed in the system
in a star configuration. If this concept is rigorously applied, it can eliminate the risk of ground
loops.
Figure 8-19
Signals are transmitted via a conducted electrical interface, which can be affected by
conducted interference. To minimize external interference, the signals are injected
asymmetrically and are floating. When this transmission method is used, the receiver
(optocoupler) receives the signal along with the reference potential from the transmitter. The
signal data is, therefore, forwarded to an optocoupler (group) via a closed loop.
The symmetrical interference is minimized by means of twisted cables (outgoing/incoming
conductors).
In general, the shield should be applied at both ends of the shield support bar.
The digital outputs of the TM15 are continued short-circuit proof. The logical status of the
outputs can be read back.
174
Potential supply of external signals
SINAMICS GM150 6SL3815-2LN41-4AA2
Operating Instructions 04/2017