succd: Migrate to KEC1 MODBUS relay board

succbone/succd/modbus.go

@@ -63,7 +63,7 @@ func (d *daemon) modbusUpdate() error {
 	d.daemonState.tempSEM = modbusValuesToFloat(registers[0])
 	d.daemonState.humiditySEM = modbusValuesToFloat(registers[1])
 
-	// Switch to slave 2
+	// Switch to slave 2 (KEC2)
 	d.modbusClient.SetUnitId(2)
 
 	// PT100 mapping
@@ -76,18 +76,74 @@ func (d *daemon) modbusUpdate() error {
 	}
 
 	if len(registers) != 3 {
-		msg := fmt.Sprintf("Expected three registers from modbus slave 2, but got %d", len(registers))
-		return errors.New(msg)
+		return fmt.Errorf("expected three registers from modbus slave 2, but got %d", len(registers))
 	}
 
 	d.daemonState.tempDPBottom = modbusValuesToFloat(registers[0])
 	d.daemonState.tempDPInlet = modbusValuesToFloat(registers[1])
 	d.daemonState.tempDPTop = modbusValuesToFloat(registers[2])
 
+	// Switch to slave 3 (KEC1)
+	d.modbusClient.SetUnitId(3)
+
+	// Do a read first to avoid side-effects from the subsequent write to the relay states
+	var digitalInputs [8]bool
+	var digitalInputRegisters []uint16
+
+	digitalInputRegisters, err = d.modbusClient.ReadRegisters(0x81, 8, modbus.HOLDING_REGISTER)
+	if err != nil {
+		return err
+	}
+	// Convert MODBUS words into bools
+	for idx, value := range digitalInputRegisters {
+		if value != 0 {
+			digitalInputs[idx] = true
+		} else {
+			digitalInputs[idx] = false
+		}
+	}
+	// TODO: Input mapping goes here
+
+	// KFA1-KFA8
+	var relayState [8]bool
+
+	// -KFA1 Roughing Pump
+	relayState[0] = d.daemonState.rpOn
+	// -KFA2 Diffusion Pump
+	relayState[1] = d.daemonState.dpOn
+	// -KFA4 Button Vent
+	relayState[3] = d.daemonState.vent.output
+	// -KFA5 Button Pump-Down
+	relayState[4] = d.daemonState.pumpdown.output
+	// -KFA6 Fake-Pirani Rough
+	relayState[5] = d.aboveRough.output
+	// -KFA7 Fake-Pirani High
+	relayState[6] = d.aboveHigh.output
+
+	// The KEC1 module uses a non-standard MODBUS interface
+	// instead of coils
+	// 0x0100 is the open command
+	// 0x0200 is the close command
+	// We write 8 words (16-bit) to address 0x01 to update the relays
+	var registerValues [8]uint16
+	// Convert the boolean values to the commands
+	for idx, state := range relayState {
+		if state {
+			registerValues[idx] = 0x0100
+		} else {
+			registerValues[idx] = 0x0200
+		}
+	}
+
+	err = d.modbusClient.WriteRegisters(0x01, registerValues[:])
+	if err != nil {
+		return err
+	}
+
 	return nil
 }
 
-// Call modbusUpdate every second
+// Call modbusUpdate every 100 milliseconds
 func (d *daemon) modbusProcess(ctx context.Context) {
 	for {
 		select {
@@ -95,7 +151,7 @@ func (d *daemon) modbusProcess(ctx context.Context) {
 			return
 		default:
 			d.modbusUpdate()
-			time.Sleep(time.Second * 1)
+			time.Sleep(time.Millisecond * 100)
 		}
 	}
 }