The VODEXL has two serial ports. However, only one port can be used for serial communication between host and device.
The other port is for diagnostic purposes only.
The serial port can be easily tested by sending an AT command to the modem.
Does the serial connection have the right configuration?
In order to establish a serial connection to the device, it is important to use the following serial interface configuration:
Baud rate: 115200
Data bits: 8
Stop bits: 1
No attach to Vodafone network
Is the SIM CHIP available?
To establish a connection to the Vodafone network, the modem of the device has to access the SIM chip.
The functionality of the SIM chip can be tested as shown below.
Is the SIM chip activated?
The SIM chip profile has to be activated by Vodafone, otherwise the device will be rejected (+CEREG: 2,3) by network.
The following figure shows an example of a scenario when the SIM chip profile is activated (+CEREG: 2,5).
USB Connect requires SIM cards specifi c to Cat M1 and NB-IoT networks. Standard 4G/LTE SIM cards, even the same form factor, may not function in this cellular modem.
Is the right MNO profile selected?
The number of bands and channels are directly addressed by MNO profiles. Hence, to connect to Vodafone network, the right MNO profiles have to selected.
The available Vodafone profiles on VODEXL are:
For the selecting the right profile see the code examples
Insufficient Internet connection
Does the hardware installation follow the instruction in the hardware manual?
The RF performance of the device highly depends on the right installation. Therefore, make sure that the application follows the instruction in the hardware manual.
How good is the radio connection to the Vodafone network?
The properties of the radio connection to the Vodafone network can be tested by the following AT Commands.
+RSRP: the Parameter in quotation marks represent the RSRP value.
+RSRQ: the Parameter in quotation marks represent the RSRQ value.
+CSQ returns the RSSI (General Signal strength)
For an analysis of the radio conncetion only RSRP and RSRQ should be considered as shown in the table below.
Rating of RF connection
Rating of RF connection
-50 dBm .. -65 dBm
-65 dBm .. -80 dBm
-4 ..-5 dB
-80 dBm .. -95 dBm
-6 .. -8 dB
-95 dBm .. -105 dBm
-9 .. -11 dB
-110 dBm ..-125 dBm
-12 .. -15 dB
-125 dBm ..-140 dBm
-16 .. -20 dB
Is it possible to establish a connection to a test server?
In order to establish a test connection, please follow the procedure in figure below.
For an investigation of a any device instability issues, please answer the following questions.
Does the application follow the specification in hardware manual?
For more information please, have a look at the hardware manual. A detailed description of the application and the hardware integration are needed.
How long does the device work until the shut down takes place?
For a detailed evaluation of the instability issues, information like mean time to failure (here shutdown) are of great interest.
Does the shut down happens before or after the first attach?
Sometimes information from the network can lead to a configuration which could be misinterpreted as a shutdown (e.g. deep sleep. See power configuration for more details).
Does the device shut down periodically?
Hereby, the reason could be misconfiguration or cyclic overload of the device. For that reason, a description of the application would be necessary for a deeper investigation.
How long is the interval between the shutdowns?
Does the device response between the shutdowns?
What are the power save configurations?
When the device periodically shuts down after the first attach to the network, the power save configuration could cause to a cyclic deep sleep of the device, which often is misinterpreted as cyclic shutdown.
This can be verified by disabling the power save functionality of the modem as shown below.