HE910 AT# SIMDET – SIM Detection Mode – when having no Detect Switch

4 thoughts on “HE910 AT# SIMDET – SIM Detection Mode – when having no Detect Switch

  1. HE910: We are using a SIM card holder without a detect switch and would like to confirm that the modem SIM block can work properly without.

    For that purpose the AT command SIMDET is used:

    0:  ignore SIMIN pin and simulate ‘SIM Not Inserted’

    1:  ignore SIMIN pin and simulate ‘SIM Inserted’

    2:  auto SIM detection via SIMIN pin (default).

    1. We understood that the Card Detect function is used for SIM hot removal.

    2. Related AT commands are:

       2.1  SIMPR – SIM Presence status,

       2.2 AT+CIMI – Internal Mobile Subscriber Identity – return ERROR if card not present.

    If we are connecting pin SIMIN to ground and using SIMDET setting 1 ‘SIM Inserted’,

    can you confirm that the HE910 can function properly with or without the SIM, please?

    Best regards,


    1. The #SIMDET command should be used instead of the SIMIN pin to simulate the SIM insertion/removal.

      Therefore it is ok to connect SIMIN to ground and use #SIMDET=1 for SIM insertion or #SIMDET=0 for SIM removal.


      I don’t understand you final question. What do you mean with  " the HE910 can function properly with or without the SIM" ?

      Without the SIM the module can work with the limitaion that it is not registered to the network, so no calls except emergency calls, no SMS, no PS data transfer.

  2. Thank you Andrea for your reply.

    We mean that we need to confirm for the Telit HE910 Modem:

    1.  Will not have abnormal functioning or uncontrolled behaviour if the SIM IN pin is grounded and the SIM not present.
    2. That effectively the SIMIN Card Detect pin is used for hot removal only.

    This in order to avoid system & HE910 software control surprises if we use a mini-SIM holder without Card Detect switch.



    1. Abnormal functioning are not expected even if SIMIN is grounded and SIM is not present. In case the SIM is not present all the SIM commands should return SIM failure.


      The SIMIN pin is normally used to detect SIM presence and allow SIM hot removal. This can be simulated by AT#SIMDET=0/1