From 3b9c1ba912e765af07e0de8a63acf3db6750878f Mon Sep 17 00:00:00 2001
From: hmelder <service@hugomelder.com>
Date: Sun, 10 Nov 2024 07:06:56 +0100
Subject: [PATCH] succd: MODBUS library does not differentiate between TCP
 socket time outs and RTU time outs

---
 succbone/succd/modbus.go | 25 +++++++++++--------------
 1 file changed, 11 insertions(+), 14 deletions(-)

diff --git a/succbone/succd/modbus.go b/succbone/succd/modbus.go
index bc7681d..4aebd03 100644
--- a/succbone/succd/modbus.go
+++ b/succbone/succd/modbus.go
@@ -2,7 +2,6 @@ package main
 
 import (
 	"context"
-	"net"
 	"time"
 
 	"github.com/simonvetter/modbus"
@@ -22,7 +21,7 @@ func (d *daemon) modbusConnect() error {
 	// Setup modbus client
 	d.modbusClient, err = modbus.NewClient(&modbus.ClientConfiguration{
 		URL:     "tcp://10.250.241.20:8887",
-		Timeout: 5 * time.Second,
+		Timeout: 1 * time.Second,
 	})
 	if err != nil {
 		return err
@@ -48,6 +47,7 @@ func (d *daemon) modbusRestart() error {
 // Returns whether modbus should restart (only in case of an underlying network error)
 func (d *daemon) modbusUpdate() bool {
 	var err error
+	var numDevicesNotResponding int
 
 	// Switch to slave 1 (BTA1)
 	d.modbusClient.SetUnitId(1)
@@ -56,9 +56,7 @@ func (d *daemon) modbusUpdate() bool {
 	var registersBTA1 []uint16 // temperature, humidity
 	registersBTA1, err = d.modbusClient.ReadRegisters(1, 2, modbus.INPUT_REGISTER)
 	if err != nil {
-		if _, ok := err.(net.Error); ok {
-			return true
-		}
+		numDevicesNotResponding += 1
 		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))
@@ -79,9 +77,7 @@ func (d *daemon) modbusUpdate() bool {
 	var registersKEC2 []uint16 // temperatures dp
 	registersKEC2, err = d.modbusClient.ReadRegisters(0, 3, modbus.HOLDING_REGISTER)
 	if err != nil {
-		if _, ok := err.(net.Error); ok {
-			return true
-		}
+		numDevicesNotResponding += 1
 		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))
@@ -102,9 +98,7 @@ func (d *daemon) modbusUpdate() bool {
 
 	digitalInputRegisters, err = d.modbusClient.ReadRegisters(0x81, 8, modbus.HOLDING_REGISTER)
 	if err != nil {
-		if _, ok := err.(net.Error); ok {
-			return true
-		}
+		numDevicesNotResponding += 1
 		klog.Warningf("error while reading digital inputs from KEC1 %v", err)
 	} else {
 		// Convert MODBUS words into bools
@@ -157,12 +151,15 @@ func (d *daemon) modbusUpdate() bool {
 
 	err = d.modbusClient.WriteRegisters(0x01, registerValuesKEC1[:])
 	if err != nil {
-		if _, ok := err.(net.Error); ok {
-			return true
-		}
+		numDevicesNotResponding += 1
 		klog.Warningf("error while updating registers %v", err)
 	}
 
+	if numDevicesNotResponding >= 4 {
+		klog.Warningf("no device did respond to our request. Probably a network timeout.")
+		return true
+	}
+
 	return false
 }