Calculating a power budget
B.1 Power budget
S7-200 SMART
654 System Manual, 09/2015, A5E03822230-AC
Some of the 24 V DC power input ports in the S7-200 SMART system are interconnected,
with a common logic circuit connecting multiple M terminals. For example, the following
circuits are interconnected when designated as "not isolated" in the data sheets: the 24 V
DC power supply of the CPU, the power input for the relay coil of an EM, or the power supply
for a non-isolated analog input. All non-isolated M terminals must connect to the same
external reference potential.
Avoiding unwanted current flow
Connecting non-isolated M terminals to different reference potentials will cause unintended
current flows that may cause damage or unpredictable operation in the PLC and any
connected equipment.
Failure to comply with these guidelines could cause damage or unpredictable operation
which could result in death or severe personal injury and/or property damage.
Always ensure that all non-isolated M terminals in an S7-200 SMART system are
connected to the same reference potential.
Refer to the technical specifications for your particular CPU (Page 570) to determine the
24 V DC sensor supply power budget, the 5 V DC logic budget supplied by your CPU and
the 5 V DC power requirements of the expansion modules and signal boards.
To Next Page
Loading...
