+UDWNFILE response time problem

0 votes

Hello there,

I am using SARA-U201. I am having problem understanding the timeout for +UDWNFILE file. According to the datasheet (UBX-13002752 - R55, Page 484 of 851, section 21.2 Download file +UDWNFILE) the response time for this command (">" sign ) is immediate:


I have noticed however that this is not entirelly true. I have noticed some delays when using the m-center program through USB, as well as using uart with the interfacing MCU. Here is an example log from my program (Uart2 is the uart peripheral connected to the SARA chip from my MCU):

[17:39:49:032] [2018-02-08T16:39:48.717Z][tNm     ]<Debug>:		ACK timeout for cmd UDWNFILE(23) set to 7 s
[17:39:49:040] [2018-02-08T16:39:48.725Z][tUartRx ]<Debug>:		UART2 RECV(01): 0A 
[17:39:49:048] [2018-02-08T16:39:48.733Z][tUartTx ]<Debug>:		UART2 SENT(69): 41 54 2B 55 44 57 4E 46 49 4C 45 3D 22 6A 73 6F 6E 5F 32 30 31 38 2D 30 32 2D 30 38... 
[17:39:55:980] [2018-02-08T16:39:55.674Z][tNm     ]<Error>:		Sara message response timeout (7000 ms)
[17:39:55:988] [2018-02-08T16:39:55.674Z][tNm     ]<Critical>:	        Fs: failed to start file entry for json_2018-02-08T16.39.48.318Z_P6W462 08-002D0028-0
[17:39:57:148] [2018-02-08T16:39:56.843Z][tUartRx ]<Debug>:		UART2 RECV(02): 0A 3E 
[17:39:57:155] [2018-02-08T16:39:56.843Z][tUartRx ]<Debug>:		Sara recv file entry: >
[17:40:17:282] [2018-02-08T16:40:16.980Z][tUartRx ]<Debug>:		UART2 RECV(09): 0D 0A 45 52 52 4F 52 0D 0A 
[17:40:17:289] [2018-02-08T16:40:16.980Z][tUartRx ]<Debug>:		Sara recv frc: ERROR


As you can see I was waiting for the response for 7 seconds, but it came after 8,115 seconds. Is the response time for this command somehow altered?

I would appreciate all help regarding this.

by bremenpl asked Feb 9
0 votes
Looking at AT commands manual I think it means response time is not defined.  Suspect it depends on network conditions and could be short or long.

Instead of placing timeouts you should wait for OK, URC or ERROR messages from the modem before doing next step.
by grumpy answered Feb 13
I do that, but I also cannot rule out the timeout and wait forever.
Then I would suggest a "reasonable" timeout.  This is a network related operation so 3 min would be reasonable but otherwise you can set it to whatever works for you and then just re-do the operation if it times out.
Reasonable timeout is fine for me, it can be any timeout. Its just that I think there is an error/ misconception in the datasheet. "-" clearly states "instant" answer.