Volume counting with AT#GDATAVOL=2

6 thoughts on “Volume counting with AT#GDATAVOL=2

  1. Hi,

     

    I’m trying to count transferred data volume with AT#GDATAVOL.

     

    Documentation
    states, that  the total session counters are stored in NVM
    (AT#GDATAVOL=2).  This is important because in our application the GSM
    module is periodically switched off.

     

     Questions:

    • chapter 3.3 of the AT Commands Reference Guide r15 does not mention GDATAVOL.  So where is it actually stored?
    • startup
      command sequence of our application does neither contain AT&F nor
      ATZ.  Querying AT#GDATAVOL=2 after providing the PIN always shows zero. 
      What’s wrong there?
    • shutdown is done with AT#SHDN.  Are there any timing requeirements to allow the module to write data to NVM?

    This all happens on a "GE864-QUAD-V2".

     

    Thanks for help & regards

     

    Hardy

     

     

    PS: where are the bookmarks in the AT Commands Reference?  In r10 they were contained while in r15 they are not… 🙁

    1. Hi,

       

      I confirm you the total GPRS counter is saved on NVM.

       

      at+gmr
      10.00.025

      OK
      at#sd=1,0,510,"xyz.xyz.xyz.xyz",0,0,0

      CONNECT
      Hello1234567890

      OK

      SRING: 1
      at#gdatavol=2
      #GDATAVOL: 1,2709,1643,1066

      OK
      at#sh=1

      OK
      at#gdatavol=2

      #GDATAVOL: 1,2789,1683,1106

      OK
      at#shdn
      OK
      at#gdatavol=2
      #GDATAVOL: 1,2789,1683,1106

      OK

      1. My sequence is a little bit longer, but I cannot see any suspicious:

         

        Modem_Puts: ATI
        Modem_Gets: 0, ATI
        Modem_Gets: 0, 332
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: ATI
        Modem_Gets: 0, ATI
        Modem_Gets: 0, 332
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: ATI1
        Modem_Gets: 0, ATI1
        Modem_Gets: 0, 0
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: ATE0;V1;+CMEE=1
        Modem_Gets: 0, ATE0;V1;+CMEE=1
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: ATQ3;&C1;&S3;&D1
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#SELINT=2;#SMSMODE=1;#REGMODE=1;#CPUMODE=2
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#SIMDET=1
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#AUTOATT=0
        Modem_Gets: 0, +CME ERROR: 10
        Modem_Cmd-Resp FAILED
        Modem_Puts: AT#AUTOATT=0
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#SIMATR
        Modem_Gets: 0, #SIMATR: 3B9E95801FC7
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#ENHSIM=0
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#QSS?
        Modem_Gets: 0, #QSS: 0,1
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#FASTCCID?
        Modem_Gets: 0, #FASTCCID: 0
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#SIMINCFG?
        Modem_Gets: 0, ERROR
        Modem_Cmd-Resp FAILED
        Modem_Puts: AT+CGMM
        Modem_Gets: 0, GE864-QUAD-V2
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CGMR
        Modem_Gets: 0, 10.00.024
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#AUTOBND=2;S12=20
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#BND?
        Modem_Gets: 0, #BND: 0
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CPIN?
        Modem_Gets: 0, +CPIN: SIM PIN
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#PCT
        Modem_Gets: 0, #PCT: 3
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CPIN=xxxx

        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CIMI
        Modem_Gets: 0, +CME ERROR: 3
        Modem_Cmd-Resp FAILED
        Modem_Puts: AT+CIMI
        Modem_Gets: 0, 228021502570867
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CNUM
        Modem_Gets: 0, +CME ERROR: 22
        Modem_Cmd-Resp FAILED
        Modem_Puts: AT+CNUM
        Modem_Gets: 0, +CME ERROR: 22
        Modem_Cmd-Resp FAILED
        Modem_Puts: AT+CNUM
        Modem_Gets: 0, +CME ERROR: 22
        Modem_Cmd-Resp FAILED
        Modem_Puts: AT+CNUM
        Modem_Gets: 0, +CME ERROR: 22
        Modem_Cmd-Resp FAILED

        Modem_Puts: AT+CNUM
        Modem_Gets: 0, +CME ERROR: 22
        Modem_Cmd-Resp FAILED
        Modem_Puts: AT+CNUM
        Modem_Gets: 0, +CME ERROR: 22
        Modem_Cmd-Resp FAILED
        Modem_Puts: AT+CNUM
        Modem_Gets: 0, +CNUM: "?","",129
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#GAUTH=3
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#GDATAVOL=1
        Modem_Gets: 0, #GDATAVOL: 1,0,0,0
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#GDATAVOL=2
        Modem_Gets: 0, #GDATAVOL: 1,0,0,0
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CSCS="GSM"
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CGSN
        Modem_Gets: 0, 357005030016990
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+COPS?
        Modem_Gets: 0, +COPS: 0,0,"SWISS GSM"
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CGCLASS?
        Modem_Gets: 0, +CGCLASS: "B"
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CGQMIN=1,0,0,0,0,0
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CGQMIN?
        Modem_Gets: 0, +CGQMIN: 1,0,0,0,0,0
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CGQREQ=1,0,0,1,0,0
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CGQREQ?
        Modem_Gets: 0, +CGQREQ: 1,0,0,1,0,0
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CPWC?
        Modem_Gets: 0, +CPWC: 5,4,0,2,1,1,2,1,2
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CPWC=5,0
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CPWC=2,1
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CPWC=2,2
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CPWC?
        Modem_Gets: 0, +CPWC: 5,4,0,2,1,1,2,1,2

        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#MSCLASS?
        Modem_Gets: 0, #MSCLASS: 1
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#MSCLASS=1,0
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#MSCLASS?
        Modem_Gets: 0, #MSCLASS: 1
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#SCFG=1,1,300,90,600,1
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: ATI4
        Modem_Gets: 0, GE864-QUAD-V2
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CGDCONT=1,"IP","internet"
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#SGACT=1,1,"internet","internet"
        Modem_Gets: 0, #SGACT: 10.131.99.216
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CSQ
        Modem_Gets: 0, +CSQ: 23,0
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+COPS?
        Modem_Gets: 0, +COPS: 0,0,"sunrise"
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#SERVINFO
        Modem_Gets: 0, #SERVINFO: 733,-67,"sunrise","22802",55,0DAC,01,1,,"II",65,6
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#MONI=7
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#MONI
        Modem_Gets: 0, #MONI: Cell  BSIC  LAC  CellId  ARFCN    Power  C1  C2  TA  RxQual  PLMN
        Modem_Gets: 0, #MONI:  S    55  0DAC   082F     733   -67dbm  29  29   1     0    sunrise
        Modem_Gets: 0, #MONI: N1    FF  FFFF   0000      95   -78dbm  -1  -1
        Modem_Gets: 0, #MONI: N2    FF  FFFF   0000     785   -81dbm  -1  -1
        Modem_Gets: 0, #MONI: N3    FF  FFFF   0000      86   -86dbm  -1  -1
        Modem_Gets: 0, #MONI: N4    FF  FFFF   0000     719   -91dbm  -1  -1
        Modem_Gets: 0, #MONI: N5    FF  FFFF   0000     880   -92dbm  -1  -1
        Modem_Gets: 0, #MONI: N6    FF  FFFF   0000     871   -95dbm  -1  -1
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#QDNS="rgrr.dnsalias.net"
        Modem_Gets: 0, #QDNS: "rgrr.dnsalias.net","84.56.233.59"
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#SD=1,0,443,"84.56.233.59"

        Modem_Gets: 0, CONNECT

        :

        Modem_Puts: +++
        Modem_Puts: ATI
        Modem_Gets: 0, 332
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#GDATAVOL=1
        Modem_Gets: 0, #GDATAVOL: 1,9528,6376,3152
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CPIN?
        Modem_Gets: 0, +CPIN: READY
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CREG?
        Modem_Gets: 0, +CREG: 0,1
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#SGACT?
        Modem_Gets: 0, #SGACT: 1,1
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CGQMIN?
        Modem_Gets: 0, +CGQMIN: 1,0,0,0,0,0
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CGQMIN=?
        Modem_Gets: 0, +CGQMIN: "IP",(0-3),(0-4),(0-5),(0-9),(0-18,31)
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CGQREQ?
        Modem_Gets: 0, +CGQREQ: 1,0,0,1,0,0
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CGQREQ=?
        Modem_Gets: 0, +CGQREQ: "IP",(0-3),(0-4),(0-5),(0-9),(0-18,31)
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#SS=1
        Modem_Gets: 0, #SS: 1,0
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#SI=1
        Modem_Gets: 0, #SI: 1,5185,1825,0,53
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#SH=1
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#GDATAVOL=2
        Modem_Gets: 0, #GDATAVOL: 1,9528,6376,3152
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#GDATAVOL=1
        Modem_Gets: 0, #GDATAVOL: 1,9528,6376,3152
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#SGACT=1,0
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CHUP
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#SERVINFO
        Modem_Gets: 0, #SERVINFO: 733,-69,"sunrise","22802",55,0DAC,00,1,,"II",65,6

        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#MONI=7
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#MONI
        Modem_Gets: 0, #MONI: Cell  BSIC  LAC  CellId  ARFCN    Power  C1  C2  TA  RxQual  PLMN
        Modem_Gets: 0, #MONI:  S    55  0DAC   082F     733   -69dbm  27  27   0     0    sunrise
        Modem_Gets: 0, #MONI: N1    66  0DAC   6601      95   -78dbm  22  22
        Modem_Gets: 0, #MONI: N2    51  0DAC   0830     785   -81dbm  15  15
        Modem_Gets: 0, #MONI: N3    56  4650   55CA      86   -86dbm  14   8
        Modem_Gets: 0, #MONI: N4    53  0DAC   0000     719   -90dbm   6   6
        Modem_Gets: 0, #MONI: N5    52  0DAC   0000     880   -93dbm  -24  -24
        Modem_Gets: 0, #MONI: N6    52  0DAC   A84E     742   -94dbm  -25  -25
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#SHDN
        Modem_Gets: 0, OK

         

         

        Modem_Puts: ATI
        Modem_Gets: 0, ATI
        Modem_Gets: 0, 332
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: ATI
        Modem_Gets: 0, ATI
        Modem_Gets: 0, 332
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: ATI1
        Modem_Gets: 0, ATI1
        Modem_Gets: 0, 0
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: ATE0;V1;+CMEE=1
        Modem_Gets: 0, ATE0;V1;+CMEE=1
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: ATQ3;&C1;&S3;&D1
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#SELINT=2;#SMSMODE=1;#REGMODE=1;#CPUMODE=2
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#SIMDET=1
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#AUTOATT=0
        Modem_Gets: 0, +CME ERROR: 10
        Modem_Cmd-Resp FAILED
        Modem_Puts: AT#AUTOATT=0
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#SIMATR
        Modem_Gets: 0, #SIMATR: 3B9E95801FC78031E073FE211B66D001380000003A
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#ENHSIM=0
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#QSS?
        Modem_Gets: 0, #QSS: 0,1
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#FASTCCID?
        Modem_Gets: 0, #FASTCCID: 0
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#SIMINCFG?
        Modem_Gets: 0, ERROR
        Modem_Cmd-Resp FAILED
        Modem_Puts: AT+CGMM
        Modem_Gets: 0, GE864-QUAD-V2
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT+CGMR
        Modem_Gets: 0, 10.00.024
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#AUTOBND=2;S12=20

         Modem_Gets: 0, OK
         Modem_Cmd-Resp is ok
         Modem_Puts: AT#BND?
         Modem_Gets: 0, #BND: 0
         Modem_Gets: 0, OK
         Modem_Cmd-Resp is ok
         Modem_Puts: AT+CPIN?
         Modem_Gets: 0, +CPIN: SIM PIN
         Modem_Gets: 0, OK
         Modem_Cmd-Resp is ok
         Modem_Puts: AT#PCT
         Modem_Gets: 0, #PCT: 3
         Modem_Gets: 0, OK
         Modem_Cmd-Resp is ok
         Modem_Puts: AT+CPIN=8080
         Modem_Gets: 0, OK
         Modem_Cmd-Resp is ok
         Modem_Puts: AT+CIMI
         Modem_Gets: 0, +CME ERROR: 3
         Modem_Cmd-Resp FAILED
         Modem_Puts: AT+CIMI
         Modem_Gets: 0, 228021502570867
         Modem_Gets: 0, OK
         Modem_Cmd-Resp is ok
         Modem_Puts: AT+CNUM
         Modem_Gets: 0, +CME ERROR: 22
         Modem_Cmd-Resp FAILED
         Modem_Puts: AT+CNUM
         Modem_Puts: AT+CNUM
         Modem_Gets: 0, +CME ERROR: 22
         Modem_Cmd-Resp FAILED
        Modem_Puts: AT+CNUM
        Modem_Gets: 0, +CME ERROR: 22
        Modem_Cmd-Resp FAILED
        Modem_Puts: AT+CNUM
        Modem_Gets: 0, +CME ERROR: 22
        Modem_Cmd-Resp FAILED
        Modem_Puts: AT+CNUM
        Modem_Gets: 0, +CME ERROR: 22
        Modem_Cmd-Resp FAILED
        Modem_Puts: AT+CNUM
        Modem_Gets: 0, +CME ERROR: 22
        Modem_Cmd-Resp FAILED
        Modem_Puts: AT+CNUM
        Modem_Gets: 0, +CNUM: "?","",129
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#GAUTH=3
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#GDATAVOL=1
        Modem_Gets: 0, #GDATAVOL: 1,0,0,0
        Modem_Gets: 0, OK
        Modem_Cmd-Resp is ok
        Modem_Puts: AT#GDATAVOL=2
        Modem_Gets: 0, #GDATAVOL: 1,0,0,0
        Modem_Gets: 0, OK

        :

         Hardy

        1. How many modules you have tested, are behaving in this way?

           

          For sure this is not a software feature of a standard module.

          Can you please check if other parameters that are normally stored in NVM are kept on no?

           

          e.g.

          AT+CGDCONT=1,"IP","internet"

          AT#MSCLASS=1,0

           

          Can you check if the values are kept after shutdown?

          1. Actually I have only one module available in my test environment.  Firmware version is 10.00.024.

             

             AT#MSCLASS behaves as expected:

             

            Modem_Puts: AT#MSCLASS?
             Modem_Gets: 0, #MSCLASS: 2
             Modem_Gets: 0, OK
             Modem_Cmd-Resp is ok
             Modem_Puts: AT#MSCLASS=3,0
             Modem_Gets: 0, OK
             Modem_Cmd-Resp is ok
             Modem_Puts: AT#MSCLASS?
             Modem_Gets: 0, #MSCLASS: 3
             Modem_Gets: 0, OK

             

            Shutdown of the module and subsequent start up of the module shows:

             

            Modem_Puts: AT#MSCLASS?
            Modem_Gets: 0, #MSCLASS: 3
            Modem_Gets: 0, OK
            Modem_Cmd-Resp is ok
            Modem_Puts: AT#MSCLASS=3,0
            Modem_Gets: 0, OK
            Modem_Cmd-Resp is ok
            Modem_Puts: AT#MSCLASS?
            Modem_Gets: 0, #MSCLASS: 3

             

            GDATAVOL shows the same as before:  after startup of the moduleit shows

             

            Modem_Puts: AT#GDATAVOL=1
            Modem_Gets: 0, #GDATAVOL: 1,0,0,0
            Modem_Gets: 0, OK
            Modem_Cmd-Resp is ok
            Modem_Puts: AT#GDATAVOL=2
            Modem_Gets: 0, #GDATAVOL: 1,0,0,0
            Modem_Gets: 0, OK

             

             Any ideas?

             

            Thanks

             

            Hardy

          2. Working together with Hardy we found the solution.

             

            #GDATAVOL=2 is stored in NVM once the PDP context is deactivated (AT#SGACT=1,0).

             

            In his application there is about one second between AT#SGACT=1,0 and AT#SHDN and after 100ms, VBATT is removed.

            When #SGACT is issued, the OK is returned immediately but the PDP deactivation procedure can take more seconds.

             

            The solution was in this case to verify with AT#SGACT? that the context was really  deactivated #SGACT: 1,0, before remove the power.

             

            In any case it is no recommended to remove the power from VBATT, 100ms after AT#SHDN since the network detach procedure can takes 2-3 seconds in normal conditions.