M-Bus

api.mbusTransaction(msg, timeout, retry)

Overview

Transmit "msg" and wait given "timeout" milliseconds for the answer. The transmission is retried "retry" times.

Turn on MBus using mbusState first.

Arguments

• msg (string) - Message sent to MBus
• timeout (integer) - The maximum time in milliseconds to wait for answer from MBus device
• retry (integer) - Optional number of retransmissions, default number is 1

Return

• status (integer) - Number of bytes received, zero on failure
• c (integer) - MBus c frame field
• a (integer) - MBus a frame field
• ci (integer) - MBus ci frame field
• answer (string) - MBus frame payload received from the bus

Example

--Send MBus frame [0x10, 0x50, 0x30, 0x16] and wait 5s for the answer twice
msg = pack.pack('<b4', 0x10, 0x50, 0x30, 0x16)
status,c,a,ci,ans = api.mbusTransaction(msg, 5000, 2)

api.mbusSetup(baudrate, parity, stopBits, dataBits)

Overview

Configures the MBus communication interface. Configuration from GUI is used by default, but it can be overriden using this function.

Turn on M-Bus using mbusState after setting up M-Bus parameters using this function.

Arguments

• baudrate (integer) - Baudrate to use for communication (up to 921600 baud)
• parity (integer) - Parity, 0 for none, 1 for odd and 2 for even parity
• stopBits (integer) - Number of stop bits, 1 or 2 allowed
• dataBits (integer) - Number of data bits, 7 or 8 allowed

Example

--setup M-Bus interface to 9600 Baud, 8E2
api.mbusSetup(9600, 2, 2, 8)

api.mbusState(state)

Overview

Turns on the M-Bus circuitry.

Use api.mbusState(1) before api.mbusTransaction() and api.mbusState(0) after to reduce consumption. The consumption significantly raises if the circuitry is turned on for too long.

Do not use the api.mbusState(1) during LoRaWAN or NB-IoT message transmition.

Arguments

• state (integer) - New state of MBus circuitry: 0 for off, 1 for on (apprx 30s power-up)

Example

api.mbusState(1) --turn on M-Bus