HL7800: Error when trying to establish connection

IoT Modules HL78
1

Hi, I have the HL7800 module and evaluation board and I have not been able to establish a connection.

This is the firmware version I have:
at+cgmr
BHL7800.1.7.13.0.20181226

I set the enabled bands to 2,4,12, which I think happened correctly:

at+kbndcfg?
+KBNDCFG: 0,00000000000000000806
+KBNDCFG: 1,0
+KBNDCFG: 2,0

The SIM card seems to be working correctly:
at+cpin?
+CPIN: READY

And I set it to its APN, which is from hologram:
at+kcnxcfg?
+KCNXCFG: 1,“GPRS”,“hologram”,"","",“IPV4”,“0.0.0.0”,“0.0.0.0”,“0.0.0.0”,0

and

at+cops?
+COPS: 0,0,“Hologram”,7

Looks like it is registered and roaming:
at+creg?
+CREG: 0,5

But when I try to follow the TCP client example in the AirPrime HL78xx, AT Commands Interface Guide I get this:

at&k3
OK

at+ktcpcfg=1,0,“www.google.com”,80
+KTCPCFG: 1

at+ktcpcnx=1
ERROR

I’ve tried several things but I always get and error when trying to connect.
Any guidance will be very much appreciated!

Regards,
Alan

2

@aislas,

I am guessing it is piggy backing on the AT&T M1 network?

A few things to try

  • Connect to a hard IP address rather than relying on a DNS resolution to happen. I have seen it before where a DNS server is not assigned and the connection fails.
  • Send at+cmee=1 before the set of commands to try to get some error codes out of the unit to work with.
  • For good measure check to see if the unit has an IP address with at+cgpaddr=1 (it has attached to LTE so it definetily should but it is for information).
  • Is the ERROR coming back immediately or a couple of seconds later? If it is immediate the issue will be internal and probably something to do with your settings, if a few seconds then it will have communicated with the network and there is something going on there.

Regards

Matt

1 Like
3

Thanks Matt,

Your suggestions were helpful, I didn’t know about the cmee and cgpaddr commands. I will keep using them going forward.

The problem was that I had differences between +KCNXCFG and +CGDCONT.
I made +KCNXCFG be consistent with CGDCONT and I was able to connect. I had missed this note in the AT Commands guide:

9.4. Connection of PDP Contexts
A PDP connection will be started when a session becomes active (e.g. +KTCPCNX) and will only bestopped if all sessions are closed or all sessions request to stop the connection. In case of session errors, the PDP connection deactivation behavior can be configured by +KIPOPT with <option_id>=3.The default setting after the module boot-up is that a PDP connection is requested to stop only when a session is closed by an Internet AT command (e.g. +KTCPCLOSE).
When a PDP context is active, the configuration of +KCNXCFG must be consistent with the configurationof +CGDCONT; otherwise, an error will be returned when creating a connection with +KCNXUP, +KCTPCNXor +KUDPCFG. Therefore, with an active PDP context, in +KCNXCFG:
• must be consistent with +CGDCONT <PDP_type>, and
• must be identical to +CGDCONT or must be set to the empty string “”.

Regards,
Alan