From 0df2610dcfcb81616661980c69d3fbfec8b26313 Mon Sep 17 00:00:00 2001
From: andig <andi@evcc.io>
Date: Thu, 6 Aug 2026 09:03:18 +0200
Subject: [PATCH] Bender: skip Mennekes 4You/4Business unsupported registers
 730/740 (#32560)

---
 charger/bender.go | 33 ++++++++++++++++++++-------------
 1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/charger/bender.go b/charger/bender.go
index 9aa8eb083..285ba1353 100644
--- a/charger/bender.go
+++ b/charger/bender.go
@@ -49,12 +49,13 @@ type sempHandler struct {
 // BenderCC charger implementation
 type BenderCC struct {
 	implement.Caps
-	conn    *modbus.Connection
-	current uint16
-	regCurr uint16
-	legacy  bool
-	log     *util.Logger
-	semp    sempHandler
+	conn      *modbus.Connection
+	current   uint16
+	regCurr   uint16
+	legacy    bool
+	mennekes4 bool
+	log       *util.Logger
+	semp      sempHandler
 }
 
 const (
@@ -135,10 +136,16 @@ func NewBenderCC(ctx context.Context, settings modbus.TcpSettings, cache time.Du
 	}
 
 	// check legacy register set
-	if _, err := wb.conn.ReadHoldingRegisters(bendRegChargePointModel, 10); err != nil {
+	var model string
+	if b, err := wb.conn.ReadHoldingRegisters(bendRegChargePointModel, 10); err != nil {
 		wb.legacy = true
+	} else {
+		model = bytesAsString(b)
 	}
 
+	// Mennekes 4You/4Business firmware closes the modbus connection on access to unsupported registers 730/740
+	wb.mennekes4 = strings.Contains(model, "4You") || strings.Contains(model, "4Business")
+
 	// check presence of metering
 	reg := uint16(bendRegActivePower)
 	if wb.legacy {
@@ -155,7 +162,7 @@ func NewBenderCC(ctx context.Context, settings modbus.TcpSettings, cache time.Du
 			implement.Has(wb, implement.PhaseVoltages(wb.voltages))
 		}
 
-		if !wb.legacy {
+		if !wb.legacy && !wb.mennekes4 {
 			if _, err := wb.conn.ReadHoldingRegisters(bendRegEVBatteryState, 1); err == nil {
 				implement.Has(wb, implement.Battery(wb.soc))
 			}
@@ -498,7 +505,7 @@ func (wb *BenderCC) getPhases() (int, error) {
 
 // identify implements the api.Identifier interface
 func (wb *BenderCC) identify() (string, error) {
-	if !wb.legacy {
+	if !wb.legacy && !wb.mennekes4 {
 		b, err := wb.conn.ReadHoldingRegisters(bendRegSmartVehicleDetected, 1)
 		if err == nil && binary.BigEndian.Uint16(b) != 0 {
 			b, err = wb.conn.ReadHoldingRegisters(bendRegEVCCID, 6)
@@ -556,13 +563,13 @@ func (wb *BenderCC) Diagnose() {
 	if b, err := wb.conn.ReadHoldingRegisters(bendRegOcppCpStatus, 1); err == nil {
 		fmt.Printf("\tOCPP Status:\t%d\n", binary.BigEndian.Uint16(b))
 	}
-	if !wb.legacy {
+	if !wb.legacy && !wb.mennekes4 {
 		if b, err := wb.conn.ReadHoldingRegisters(bendRegSmartVehicleDetected, 1); err == nil {
 			fmt.Printf("\tSmart Vehicle:\t%t\n", binary.BigEndian.Uint16(b) != 0)
 		}
-	}
-	if b, err := wb.conn.ReadHoldingRegisters(bendRegEVCCID, 6); err == nil {
-		fmt.Printf("\tEVCCID:\t%s\n", b)
+		if b, err := wb.conn.ReadHoldingRegisters(bendRegEVCCID, 6); err == nil {
+			fmt.Printf("\tEVCCID:\t%s\n", b)
+		}
 	}
 	if b, err := wb.conn.ReadHoldingRegisters(bendRegUserID, 10); err == nil {
 		fmt.Printf("\tUserID:\t%s\n", b)