succd: do not early return on error in modbusUpdate

succbone/succd/modbus.go

@@ -2,11 +2,10 @@ package main
 
 import (
 	"context"
-	"errors"
-	"fmt"
 	"time"
 
 	"github.com/simonvetter/modbus"
+	"k8s.io/klog"
 )
 
 func modbusValuesToFloat(v uint16) float32 {
@@ -39,7 +38,7 @@ func (d *daemon) modbusConnect() error {
 // There are currently two devices connected to the modbus.
 // The first one (slave 1) is a temperature/humidity sensor.
 // The second one (slave 2) is a PTA8D08 transmitter
-func (d *daemon) modbusUpdate() error {
+func (d *daemon) modbusUpdate() {
 	var err error
 
 	// Switch to slave 1 (BTA1)
@@ -49,19 +48,16 @@ func (d *daemon) modbusUpdate() error {
 	var registersBTA1 []uint16 // temperature, humidity
 	registersBTA1, err = d.modbusClient.ReadRegisters(1, 2, modbus.INPUT_REGISTER)
 	if err != nil {
-		return err
+		klog.Warningf("error while reading registers from BTA1 %v", err)
+	} else if len(registersBTA1) != 2 {
+		klog.Warningf("expected two registers from modbus slave 1, but got %d", len(registersBTA1))
+	} else {
+		d.mu.Lock()
+		d.daemonState.tempSEM = modbusValuesToFloat(registersBTA1[0])
+		d.daemonState.humiditySEM = modbusValuesToFloat(registersBTA1[1])
+		d.mu.Unlock()
 	}
 
-	if len(registersBTA1) != 2 {
-		msg := fmt.Sprintf("Expected two registers from modbus slave 1, but got %d", len(registersBTA1))
-		return errors.New(msg)
-	}
-
-	d.mu.Lock()
-	d.daemonState.tempSEM = modbusValuesToFloat(registersBTA1[0])
-	d.daemonState.humiditySEM = modbusValuesToFloat(registersBTA1[1])
-	d.mu.Unlock()
-
 	// Switch to slave 2 (KEC2)
 	d.modbusClient.SetUnitId(2)
 
@@ -72,19 +68,17 @@ func (d *daemon) modbusUpdate() error {
 	var registersKEC2 []uint16 // temperatures dp
 	registersKEC2, err = d.modbusClient.ReadRegisters(0, 3, modbus.HOLDING_REGISTER)
 	if err != nil {
-		return err
+		klog.Warningf("error while reading registers from KEC2 %v", err)
+	} else if len(registersKEC2) != 3 {
+		klog.Warningf("expected three registers from modbus slave 2, but got %d", len(registersKEC2))
+	} else {
+		d.mu.Lock()
+		d.daemonState.tempDPBottom = modbusValuesToFloat(registersKEC2[0])
+		d.daemonState.tempDPInlet = modbusValuesToFloat(registersKEC2[1])
+		d.daemonState.tempDPTop = modbusValuesToFloat(registersKEC2[2])
+		d.mu.Unlock()
 	}
 
-	if len(registersKEC2) != 3 {
-		return fmt.Errorf("expected three registers from modbus slave 2, but got %d", len(registersKEC2))
-	}
-
-	d.mu.Lock()
-	d.daemonState.tempDPBottom = modbusValuesToFloat(registersKEC2[0])
-	d.daemonState.tempDPInlet = modbusValuesToFloat(registersKEC2[1])
-	d.daemonState.tempDPTop = modbusValuesToFloat(registersKEC2[2])
-	d.mu.Unlock()
-
 	// Switch to slave 3 (KEC1)
 	d.modbusClient.SetUnitId(3)
 
@@ -94,17 +88,18 @@ func (d *daemon) modbusUpdate() error {
 
 	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
+		klog.Warningf("error while reading digital inputs from KEC1 %v", err)
+	} else {
+		// 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
 	}
-	// TODO: Input mapping goes here
 
 	// KFA1-KFA8
 	var relayState [8]bool
@@ -140,10 +135,8 @@ func (d *daemon) modbusUpdate() error {
 
 	err = d.modbusClient.WriteRegisters(0x01, registerValuesKEC1[:])
 	if err != nil {
-		return err
+		klog.Warningf("error while updating registers %v", err)
 	}
-
-	return nil
 }
 
 // Call modbusUpdate every 100 milliseconds