Modbus Loop API

Modbus Loop API

• Setup a Modbus Loop
• Read Holding Registers (FC 03)
• Read Input Registers (FC 04)
• Start the loop
• Stop the loop
• Events
• Optimization

Setup a Modbus Loop

loop = new ModbusLoop(client);

• client A ModbusClient Instance.

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Register Function Calls

Read Holding Registers (FC 03)

loop.readHoldingRegisters(start, count)

• start Start Address for the Holding Registers to be read.
• count Number of Registers to be read.
• Returns the loop object.

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Read Input Registers (FC 04)

loop.readInputRegisters(start, count)

• start Start Address for the Input Registers to be read.
• count Number of Registers to be read.
• Returns the loop object.

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Start the loop

loop.start()

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Stop the loop

loop.stop()

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Events

loop.on('update', function (inputRegisters, holdingRegisters) { ... });

When every request for the input and holding registers has finished the update event will be fired. You can get your desired data from the inputRegisters and holdingRegisters Parameter.

loop.on('error', function (err) { ... });

Normally fired when there is an unexpected error on the Modbus Client. The loop will be stopped.

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Optimization

The Modbus Loop will automatically optimize your requests. So when you register

loop.readInputRegisters(0, 10)

and

loop.readInputRegisters(10, 10)

the request that is actually been send through the client is

client.readInputRegisters(0, 20)

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