Operation

Server configuration

There are two different activation types for LoRaWAN - Over-the-air activation (OTAA) and Activation by personalization (ABP). Elvaco strongly recommends using OTAA, where all network keys are generated each time the module joins the LoRaWAN network. In contrast, for ABP, all keys are set manually and stay constant over time.

In OTAA mode

Before the module is able to transmit messages via the LoRaWAN network, device information needs to be added to the network server. More specifically, the following parameters needs to be registered in order to enable the network server to receive messages from the module:

Device EUI

The device EUI is a 16 digit module unique identification number. It is not configurable.

Application key

The application key of each device is generated by Elvaco and used in OTAA mode to generate network keys when the module joins the LoRaWAN network. Keys are managed in a secure way using Elvaco’s OTC (One Touch Commissioning) solution which includes the mobile application for configuration.

Join EUI

The Join EUI sets the identification number of the application server where data from the module shall be delivered. The identification number is set to a default value in all devices. The default value is presented in Elvaco OTC configuration options.

In ABP mode

If the activation mode is set to ABP, the application key does not need to be added to the network server. Instead the following information will be needed:

  • Network session key

  • Application session key

  • Device address

Configuration

Via Elvaco OTC app

Tip

If the module is installed in the meter, the NFC field is easiest accessible if placing your smartphone at the lower part on the right hand side of the meter.

Via downlink

Transmit interval

The transmit interval is used to set how frequently the module should transmit data on the LoRaWAN network. The parameter can be set to a value between 5 and 1440 minutes (i.e. between 5-minute and daily values).

Transmit interval in EcoMode

Transmit interval for different data rates

Table 76. Data rate and transmit interval FW < 1.07

Data rate

Transmit interval

DR0

60 minutes

DR1 - DR2

30 minutes

DR3 - DR5

15 minutes


Table 77. Data rate and transmit interval FW >= 1.07

Data rate

Transmit interval

DR0

120 minutes

DR1 - DR2

60 minutes

DR3 - DR5

30* minutes


*Since Extended+ is scheduled the minimum practical limit is always 60 minutes.

Setting the transmit interval manually

If the transmit interval needs to be set to a fixed value, EcoMode can be disabled. Use the Elvaco OTC App to configure the transmit interval.

Note

If EcoMode has been disabled, guarantees about battery-life no longer apply, even if EcoMode is activated later on.

Setting an upper limit for number of daily telegrams

In some cases, it might be necessary to limit the number of daily telegrams that the module should be allowed to send. By using the MaxDTx parameter, such a limit can be easily set. For example, by setting MaxDTx to “24”, no more than 24 telegrams will be transmitted each day (regardless of the data rate).

Table 78. Examples of MaxDTx setting

MaxDTx value

Maximum transmit interval

1

Once per day

24

Once per hour

48

Once per 30 minutes

96

Once per 15 minutes


Note

To achieve a battery life time of 16+1 (storage) years, the MaxDTx parameter needs to be set to 9 or lower.

Time handling

The module relies on the meter’s clock for keeping time. Time in the meter is assumed to be in standard local time (no DST). When synchronizing time in the meter using the OTC App, local standard time is always used, even if DST is in effect. The timestamped meter data sent from the module can be adjusted to be sent in UTC by specifying the “UTC offset” configuration parameter. The UTC offset will be subtracted from the timestamp prior to transmission. If the meter is in Sweden, which uses CET (Central European Time), it should have UTC offset set to +60 (+1h). In this case at time 12.00 a telegram is sent with timestamp 11.00 as this is the corresponding UTC time. A meter in New York (USA) should have a UTC offset of -300 (-5h) etc. A UTC offset of 0 means the meter time is used as-is.

If the meter is set to used DST this is ignored by the module and the standard time is used. Thus, the time on the meter’s display may not match the time in the telegram or in the OTC App.

Adaptive data rate (ADR)

ADR is part of the LoRaWAN standard where the network server determines the optimal rate of communication for the module based on current signal conditions. In the best radio conditions, the module will use its highest data rate (DR5) in order to be as energy-efficient as possible. When signal conditions are poor, the network server will incrementally lower the data rate until it is able to receive the message. When the data rate is low, the energy consumption per telegram will increase.

Message encoding

All message formats encoded to M-bus standard will have the following structure. Each telegram begins with one byte specifying the message format. Then follows a sequence of data information blocks (DIBs). The data and structure of the DIBs depends on the message type set. Each DIB contains a data information field (DIF), a value information field (VIF) and a data field (DATA), where the actual payload is stored.

Message_structure_m-bus_.png

M-Bus message structure

For message type JSON, the data is presented as plain text.

Security and access control

The product has a configuration lock feature, which prevents unauthorized access to the module. When configuration lock has been enabled, a device-specific Product Access Key (PAK) will be needed to access the device. Keys are managed in a secure way using Elvaco’s OTC solution which includes the mobile application for configuration.

Note

For more information about security and access control for the product, refer to the One-touch commissioning (OTC) documentation, available on the Elvaco website.

Meter communication error messages

When CMi4110 is unable to communicate with UH50/UC50, an error message will be transmitted on the LoRaWAN network. Refer to the following table for description of that error message for each message type.

Table 79. Meter communication error message

Message type

Error message

Standard

0E00

Compact

0E00

JSON

{ }

Scheduled-daily redundant

0E00

Scheduled – extended +

0E00

Compact tariff

0E00


Reset procedures

Rebooting the module

  1. Press and hold the push button for 5-15 seconds.

  2. Release the button when the green LED is lit.

Led_indications_mcm_reboot__switch_off_.png

Switching off the module

  1. Press and hold the push button for 15-20 seconds.

  2. Release the button when the red LED is lit.

Led_indications_mcm_reboot__switch_off_.png

Soft starting the module

In rare cases, if the battery is weak, the module will perform a soft start to be able to start-up despite the condition of the battery. The soft start takes 10 minutes to complete. The red LED will blink shortly every 10th second until the start-up has completed.

LED_indications_soft_start_.png

LED indications when soft starting the module

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