Siemens S7-1200 - Page 987

Calculating a power budget
S7-1200 Programmable controller
System Manual, 03/2014, A5E02486680-AG
987
Table B- 1 Sample power budget
CPU power budget
5 VDC
24 VDC
CPU 1214C AC/DC/Relay
1600 mA
400 mA
Minus
System requirements
5 VDC
24 VDC
CPU 1214C, 14 inputs
-
14 * 4 mA = 56 mA
1 SB 1223 2 x 24 VDC Input/ 2 x
24 VDC Output
50 mA 2 * 4 mA = 8 mA
1 CM 1241 RS422/485, 5 V power
220 mA
3 SM 1223, 5 V power
3 * 145 mA = 435 mA
-
1 SM 1221, 5 V power
1 * 105 mA = 105 mA
-
3 SM 1223, 8 inputs each
-
3 * 8 * 4 mA = 96 mA
3 SM 1223, 8 relay coils each
-
3 * 8 * 11 mA = 264 mA
1 SM 1221, 8 inputs each
-
8 * 4 mA = 32 mA
Total requirements
810 mA
456 mA
Equals
Current balance
5 VDC
24 VDC
Current balance total 790 mA (56 mA)
Form for calculating your power budget
Use the following table to determine how much power (or current) the S7-1200 CPU can
provide for your configuration. Refer to the technical specifications (Page 829) for the power
budgets of your CPU model and the power requirements of your signal modules.
Table B- 2 Calculations for a power budget
CPU power budget
5 VDC
24 VDC
Minus
System requirements
5 VDC
24 VDC
Total requirements
Equals
Current balance
5 VDC
24 VDC
Current balance total