User Manual

AWS IoT ExpressLink SARA-R5 Starter Kit - Getting started
UBX-21042016 - R02 Troubleshooting Page 17 of 20
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7 Troubleshooting
Problem
Action
No lights come on.
Ensure power is supplied to the board, e.g., via the USB-C connector.
No welcome message is displayed when an
AT terminal application is attached to the
board.
Check that the white LED marked “On” is illuminated; the cellular module does
NOT come on automatically when the board is powered, you must press the
“SARA On” button for around one second to power the module on.
Also make sure that the baud rate of your terminal application is set to 115200.
I don’t see anything in the terminal
application when I type in it.
The AWS IoT ExpressLink specification does not include echoing of received
characters, which is normal for a “machine”-oriented interface; when typing in
commands manually, please set “local echo” on in your terminal application so
that you can see what you’re doing.
I can’t use backspace or delete or the cursor
keys to edit my AT commands when typing
in the terminal application.
The AWS IoT ExpressLink specification does not support use of editing keys; it
is meant to be used by a microcontroller, another machine, which would have no
use for editing keys. If you find this irritating when typing in commands
manually, then you should find a terminal application that holds the entire
command string locally, in the application, allowing you to edit it, and only sends
the command string once <return> is pressed.
No response is received to any AT
commands typed in the terminal
application.
Make sure that the baud rate of your terminal application is set to 115200 and
that AT commands are formed exactly as defined in the
AWS IoT ExpressLink
programmers manual
: the line ending must be line feed (0x0a); carriage return
(0x0d) and carriage return followed by line feed (0x0d 0a) cannot be used.
The AT command CONNECT does not work.
Make sure that the supplied SIM card is inserted in the board, an antenna is
connected to the antenna socket on the board (the one marked “LTE”,
not the
GNSS one) and that you are within
range of a cellular network that provides
LTE-M coverage
.
Make sure that you have followed the registration procedure of section 5,
including registering your device in your AWS account; the connection is to the
endpoint of the device in that account (not just the cellular network) and so it
cannot succeed until all of the registration steps have been completed.
If CONNECT has worked in the past but is now failing in the same location and
after using the device for some while, it may be that the cellular network has
decided to refuse service for a “guard time” (e.g. 1 hour) because the device has
connected and disconnected [again] more than a handful of times in quick
succession; unfortunately there is nothing that can be done about this (other
than avoiding many connections/disconnections), it is a network “feature”.
The AT command SEND returns OK even
when I have disconnected the cellular
antenna and so I am plainly not in coverage.
Messages are queued until it is possible to send them; if you reconnect the
cellular antenna, you should find that the messages will be successfully
published. If you do not do so, or you disconnect or reset the device, the queued
messages will be lost.
Setting a topic with the AT command CONF
TopicX (where X is 1 to 16) returns an error.
While a topic is subscribed-to it cannot be modified; please use the AT command
UNSUBSCRIBEX to unsubscribe from topic X before modifying it.
The AT commands CONFMODE, OTA,
HOTA and WHERE do not work.
These AT commands are not supported in this preview release.
Some parameters to the CONF command do
not work.
Only parameters that are relevant to a cellular device, and are not required only
by OTA or HOTA, are supported; see section 8 for a full list.
Issuing the SLEEP AT command does not
reduce the power consumption of the board.
In this preview release the SLEEP command is accepted for compatibility
purposes but does not actually put any hardware into a low power state.
The AT command TIME? does not work.
You must be connected to the cellular network to obtain the time. If the problem
happens when you
are connected, then the cellular network you are using does
not support reporting of time to the mobile terminal (the feature is optional in
the network).
Some downlink messages from the server
are going missing.
Make sure that no downlink message exceeds 2048 bytes in size; in this release
any downlink message larger than 2048 bytes in size will be silently discarded.
Messages larger than around 512 bytes in
size cannot be sent.
The maximum AT command length in this release is 512 bytes and hence this
limits the maximum length of MQTT message that can be sent.