102 lines
2.2 KiB
Go
102 lines
2.2 KiB
Go
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package main
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import (
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"context"
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"errors"
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"fmt"
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"time"
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"github.com/simonvetter/modbus"
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)
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func modbusValuesToFloat(v uint16) float32 {
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return float32(v) / 10.0
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}
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func (d *daemon) modbusConnect() error {
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var err error
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d.mu.Lock()
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defer d.mu.Unlock()
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// Setup modbus client
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d.modbusClient, err = modbus.NewClient(&modbus.ClientConfiguration{
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URL: "tcp://10.250.241.20:8887",
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Timeout: 5 * time.Second,
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})
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if err != nil {
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return err
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}
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// Connect to modbus client
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err = d.modbusClient.Open()
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if err != nil {
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return err
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}
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return nil
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}
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// There are currently two devices connected to the modbus.
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// The first one (slave 1) is a temperature/humidity sensor.
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// The second one (slave 2) is a PTA8D08 transmitter
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func (d *daemon) modbusUpdate() error {
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d.mu.Lock()
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defer d.mu.Unlock()
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var err error
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var registers []uint16 // temperature, humidity
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// Switch to slave 1
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d.modbusClient.SetUnitId(1)
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// Read temperature and humidity
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registers, err = d.modbusClient.ReadRegisters(1, 2, modbus.INPUT_REGISTER)
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if err != nil {
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return err
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}
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if len(registers) != 2 {
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msg := fmt.Sprintf("Expected two registers from modbus slave 1, but got %d", len(registers))
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return errors.New(msg)
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}
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d.daemonState.tempSEM = modbusValuesToFloat(registers[0])
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d.daemonState.humiditySEM = modbusValuesToFloat(registers[1])
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// Switch to slave 2
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d.modbusClient.SetUnitId(2)
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// PT100 mapping
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// Channel 0: Cable -WGA6, Sensor "dp bottom"
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// Channel 1: Cable -WGA8, Sensor "dp inlet"
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// Channel 2: Cable WGA7, Sensor "dp top"
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registers, err = d.modbusClient.ReadRegisters(0, 3, modbus.HOLDING_REGISTER)
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if err != nil {
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return err
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}
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if len(registers) != 3 {
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msg := fmt.Sprintf("Expected three registers from modbus slave 2, but got %d", len(registers))
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return errors.New(msg)
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}
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d.daemonState.tempDPBottom = modbusValuesToFloat(registers[0])
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d.daemonState.tempDPInlet = modbusValuesToFloat(registers[1])
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d.daemonState.tempDPTop = modbusValuesToFloat(registers[2])
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return nil
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}
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// Call modbusUpdate every second
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func (d *daemon) modbusProcess(ctx context.Context) {
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for {
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select {
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case <-ctx.Done():
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return
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default:
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d.modbusUpdate()
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time.Sleep(time.Second * 1)
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}
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}
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}
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