# Bit number (P-AXIS-00425)

P-AXIS-00425 | Bit number of signal 'Drive is referenced' during reference monitoring
Description | In this parameter enter the number of the bit which is used for transmission of the signal 'Drive is referenced' from the drive to the controller during active reference monitoring. The least significant bit has bit number 0. The maximum value depends on the length of the configured telegram element which is used for transmission.
Length of telegram element | Max. bit number
-1 | No reference monitoring
2 | 15
4 | 31
Setting the parameter to an invalid bit number leads to the output of error message P-ERR-110549.
Parameter | antr.reference_check.bit_nr
Data type | SGN16
Data range | 0 ≤ bit_nr ≤ Max. bit number
Axis types | T, R, S
Dimension | T: ---- | R,S: ----
Default value | -1
drive types. | SERCOS
Remarks | This parameter is supported for SERCOS drive types only.