Siemens S7-300 appendix Inputs not connected, Outputs not connected

Technical data of CPU 31xC

6.6 Technical data of the integrated I/O

Example of a 60-Hz parasitic frequency suppression (integration time corresponds to 16.7 ms)

1.05 ms	1.05 ms	1.05 ms	1.05 ms	1.05 ms
			. . .
Cycle 1
Value	Value	Value	Value	Value
1	2	3	16	17

1 averaged measured value

1.05 ms	1.05 ms	1.05 ms	1.05 ms	1.05 ms
			. . .
Cycle 2
Value	Value	Value	Value	Value
1	2	3	16	17

1 averaged measured value

Figure 6-6 60 Hz interference suppression

Note

If the interference frequency is not 50/60 Hz or a multiple thereof, the input signal must be filtered externally.

In this case, 400 Hz frequency suppression must be configured for the respective input. This is equivalent to a "Deactivation" of the software filter.

Inputs not connected

The three inputs of a current/voltage analog output channel that is not connected should be bypasses and connected to MANA (pin 20 of the front connector). This ensures maximum interference resistance for these analog inputs.

Outputs not connected

In order to disconnect unused analog outputs from power, you must disable and leave them open during parameter assignment with STEP 7.

Reference

Details (visualization and processing of analog values, for example) are found in chapter 4 of the Module Data Reference Manual.

6-38	CPU 31xC and CPU 31x, Technical data
	Manual, Edition 08/2004, A5E00105475-05