Sim900B dont detect sim-card when re-insert

[ThiVu]

I posted my problem here: https://www.edaboard.com/threads/221455/#post957532
But It has not yet resolved.
Now, I post again
Please kindly help me


My modem and sim-card are working normally.
Then i desert sim-card out of slot. Then I send "CPIN?", it respond "sim not insert".
Then I insert sim card.
Send "CPIN?", it respond the same as before.
I power down then power up the module then send "CPIN?" again. It respond RDY. It is OK.

My question is:
Are there any other way to connect again to sim card without re-power up (power down then power up) module because it take about 8 seconds. It is so long for my application.

Thank you!

 

[alexan_e]

Some of the post are never answered but that doesn't mean that you can repost duplicates until you receive the answer.
I have deleted the other post which I consider as a duplicate and you are warned not to repeat this in the future.

Alex

 

[ThiVu]

I find out another way to solved this problem.
I send command AT+CFUN=1,1 to restart module, it take time out about 4s.
Then I can detect simcard.
But This command respond:
IIII
RDY

OK

+CFUN: 1

+CPIN: READY
But, as in ATC Manual, It only respond OK if in fixed baudrate. The first 4 characters I think it is "OK\r\n", but it display failed.
When I switch to auto-baud, It only respond: IIIIII
So I dont check the respond to send next command.

 

[binjet7]

I want to switch SIM card "hot",

i use at_command to check SIM card:

"AT+CPIN?\r"

i feel:
modulSIM900 can automatic to understand:
if ModulSIM has got SIM Card ("respond : +CPIN: READY") and ModulSIM work normally (call, send SMS...).

if ModulSIM hasn't got SIM Card ("respond : +CPIN:NOT READY"") and ModulSIM don't work normally(don't call, send SMS..).

---------------------------------------------------------
Almost case is OK, no problem.

But sometime, there is SIM Card in ModulSIM and "respond : +CPIN: READY" -> ModulSIM don't work normally(don't call, send SMS..).

I try to by way: send atcomand: "AT+CFUN=1,1\r" and delay 2 second ( i try 1second, but not ok) -> ModulSIM work normally.

Can you help me explain this problem, i don't want to delay time > 1s. This is correct way to switch SIM "hot"?, can you show me the another way?