Large delay in some AT commands

New to the HL7800 series… Using a MangOH red for testing. The device is now connected to the network and in a data session. I do have a good IP address. However, it has not registered with AirVantage yet.

Looking over the documents, it looks like I can force a connection by entering: AT+WDSS=1,1

However, after I enter this command, I can not enter any more commands in the terminal for about 3 - 5 minutes. Then when I can type again, it tells me: “waiting for previous at command event.”

In order to enter any more AT commands, I have to reset the device. This does not happen with all the commands, only a few.

Any idea why it hangs on some AT commands?

Hi @tremmert,
Maybe you can provide a bit more details to help understand the situation
Which firmware are you working?
Which operator are you working?
Can you check credential by command:
Possible answer:
+WDSG: 0,0 ==> No credential loaded
+WDSG: 0,x (x>0) ==> Credential loaded

Sure, here are the details on the chip

Core : RKAPP_02_01_01_00_37__76cc94b4672ac9bde0f08de3724a5c20b28bc2ba
Package : RK_02_01_01_00_41
Chip Revision: TG-D0 (4)
SWIVer : BHL78xx.

I am using AT&T as the operator.

However, when I issue your next command (AT+WDSG), the device hangs…


After about 4 minutes, it responded with the following:

(about a 4 minute delay right here)
not received respond from AT command:AT+WDSG

Hi @tremmert ,
It looks like your module is getting stuck with all AT commands relating AvMS. It cannot load this function. Please upgrade to latest firmware following below link and try again. Note, you can use for your operator

Firmware upgraded…

Core : RKAPP_02_01_02_00_69__020c71aff64756af95a5cf48eba6659dcae12247
Package : RK_02_01_02_00_74
Chip Revision: TG-D0 (4)
SWIVer : HL78xx.
Flash Info : ID 0x20bb18, Size 0x1000000

However, specific commands are still hanging…

(and it hangs right here)
not received respond from AT command:AT+WDSG

Hi @tremmert,
Have you tried AT+WDSI command? Any response ? It no, looks like the function doesn’t work on your module. We recommend you contact your local distributor or reseller for technical support.
Please share if you have any concern and tick Solution if your question is answered

1 Like

is it normal to have to enter “at” before every AT command?

No, just enter AT command like this at+wdsg. Dont enter anything in front of each AT command


So for HL78 you will only use the AV server for FOTA. Steps I would recommend you do.

  • Upgrade to 4.3.9 which you have already done.
  • Register the unit to your account on the AV server, if you do not then the authentication will fail.
  • Set at+wdsi=4479, this will cause the unit to output unsolicited responses showing you what it is currently doing with regards the AV connection.



Just wanted to post an update so anyone with this same issue would know the resolution… I assumed I would be able to communicate and issue all AT commands via the two USB ports on the MangOH red board. That is incorrect. I had to purchase a 3rd purchase a 3rd party UART to RS232 board to issue AT commands and get the board to register with AV.

I am still unsure of the purpose of the two USB cables and the limited AT commands that are available however…