This FAQ applies only to the SINAMICS G120/G120D Control Units without “-2” in the product name and MICROMASTER 4 inverters.

The following example explains how to switch between fixed frequency operation and analogue setpoint:

Set the fixed frequency as the main setpoint and the analogue as the additional setpoint (P1000 = 23).
Normally the main setpoint and the additional setpoint sum together in the setpoint channel. To switch between both frequencies you have to enable or disable the particular frequency. Parameterize a digital input (e.g. DIN 3) to disable the additional setpoint (P1074) and sets the fixed frequency (P1022).

relevant parameter 

Function	Parameter	Description	Setting	Description
User access level	P0003	Defines user access level to parameter sets	3	Allows extended access
Selection of frequency setpoint	P1000	Selects frequency setpoint source (main setpoint + additional setpoint)	23	Fixed frequency + Analog setpoint
Fixed frequency 3	P1003	Defines fixed frequency	e.g. 10Hz
Function of digital input 3	P0703	Selects function of digital input 3	99	Enable BICO parameterization
Fixed freq. selection Bit 2	P1022	Defines origin of fixed frequency selection	722.2	DIN 3
Disable additional setpoint	P1074	Disables additional setpoint	722.2	DIN 3

Result:

• DIN 1 = ON / OFF 1
• DIN 2 = reverse
• DIN 3 = enable fixed frequency / disable additional setpoint