Repository: edgexfoundry/device-modbus-go (go)

Issue:
TCP Broken pipe on disconnect / reconnect
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# 🐞 Bug Report

### Affected Services [**REQUIRED**]
The issue is located in:  *device-modbus-go*


### Is this a regression?

Kinda.

The code at v3.1 used to open and close connection for each read request, which would give problems at high freqnency polls for certain devices. The current fix of using a client map keeps a persistent connection. Now in case the connection ever drops even temporarily, read/write requests fails until the container is restarted.

### Description and Minimal Reproduction [**REQUIRED**]

Connect any modbus device over TCP and start polling such as through autoevents. Disconnect and reconnect the device to the network.

## 🔥 Exception or Error
<pre><code>
level=ERROR ts=2025-01-15T11:51:55.458149687Z app=device-modbus source=executor.go:55 msg="AutoEvent - error occurs when reading resource DI8: error reading Regex DeviceResource(s) DI8 for DVC_1 -> write tcp 172.18.0.10:55972->XXX.XXX.XXX.XXX:502: write: broken pipe"
2025/01/15 17:21:55 modbus: sending 0b 32 00 00 00 06 03 02 00 0d 00 01
level=INFO ts=2025-01-15T11:51:55.459155047Z app=device-modbus source=driver.go:137 msg="Read command failed. Cmd:DI13 err:write tcp 172.18.0.10:55972->XXX.XXX.XXX.XXX:502: write: broken pipe \n"
level=ERROR ts=2025-01-15T11:51:55.459204454Z app=device-modbus source=executor.go:55 msg="AutoEvent - error occurs when reading resource DI13: error reading Regex DeviceResource(s) DI13 for DVC_1 -> write tcp 172.18.0.10:55972->XXX.XXX.XXX.XXX:502: write: broken pipe"
2025/01/15 17:21:55 modbus: sending 0b 33 00 00 00 06 03 02 00 0c 00 01
level=INFO ts=2025-01-15T11:51:55.459254348Z app=device-modbus source=driver.go:137 msg="Read command failed. Cmd:DI12 err:write tcp 172.18.0.10:55972->XXX.XXX.XXX.XXX:502: write: broken pipe \n"
level=ERROR ts=2025-01-15T11:51:55.459301749Z app=device-modbus source=executor.go:55 msg="AutoEvent - error occurs when reading resource DI12: error reading Regex DeviceResource(s) DI12 for DVC_1 -> write tcp 172.18.0.10:55972->XXX.XXX.XXX.XXX:502: write: broken pipe"
2025/01/15 17:21:55 modbus: sending 0b 34 00 00 00 06 03 02 00 09 00 01
level=INFO ts=2025-01-15T11:51:55.459347214Z app=device-modbus source=driver.go:137 msg="Read command failed. Cmd:DI9 err:write tcp 172.18.0.10:55972->XXX.XXX.XXX.XXX:502: write: broken pipe \n"
</code></pre>


## 🌍  Your Environment
**Deployment Environment:**

**EdgeX Version [**REQUIRED**]:**
Latest code at commit [2f075c7](https://github.com/edgexfoundry/device-modbus-go/commit/2f075c7931a58d709b8688ebd481c390ae67f934)

**Anything else relevant?**



Pull request description:
fix: Remove client when command failed
if command failed, remove the Modbus client from the cache to allow re-establish connection next time

fixes #606

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**If your build fails** due to your commit message not passing the build checks, please review the guidelines here: https://github.com/edgexfoundry/device-modbus-go/blob/main/.github/Contributing.md

## PR Checklist
Please check if your PR fulfills the following requirements:

- [x] I am not introducing a breaking change (if you are, flag in conventional commit message with `BREAKING CHANGE:` describing the break)
- [x] I am not introducing a new dependency (add notes below if you are)
- [ ] I have added unit tests for the new feature or bug fix (if not, why?) not impact
- [x] I have fully tested (add details below) this the new feature or bug fix (if not, why?)
- [ ] I have opened a PR for the related docs change (if not, why?) not impact
  <link to docs PR>

## Testing Instructions
<!-- How can the reviewers test your change? -->
- Deploy core services, device-modubs, modbus sim
- Test command, restart modbus-sim, and test command again. 

## New Dependency Instructions (If applicable)
<!-- Please follow [vetting instructions](https://wiki.edgexfoundry.org/display/FA/Vetting+Process+for+3rd+Party+Dependencies) and place results here -->

Patch:
diff --git a/go.mod b/go.mod
index efff5db..e173495 100644
--- a/go.mod
+++ b/go.mod
@@ -3,8 +3,8 @@ module github.com/edgexfoundry/device-modbus-go
 go 1.23
 
 require (
-	github.com/edgexfoundry/device-sdk-go/v4 v4.0.0-dev.25
-	github.com/edgexfoundry/go-mod-core-contracts/v4 v4.0.0-dev.28
+	github.com/edgexfoundry/device-sdk-go/v4 v4.0.0-dev.24
+	github.com/edgexfoundry/go-mod-core-contracts/v4 v4.0.0-dev.26
 	github.com/goburrow/modbus v0.1.0
 	github.com/spf13/cast v1.7.1
 	github.com/stretchr/testify v1.10.0
@@ -17,11 +17,11 @@ require (
 	github.com/cenkalti/backoff/v4 v4.3.0 // indirect
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
 	github.com/eclipse/paho.mqtt.golang v1.5.0 // indirect
-	github.com/edgexfoundry/go-mod-bootstrap/v4 v4.0.0-dev.28 // indirect
+	github.com/edgexfoundry/go-mod-bootstrap/v4 v4.0.0-dev.27 // indirect
 	github.com/edgexfoundry/go-mod-configuration/v4 v4.0.0-dev.14 // indirect
 	github.com/edgexfoundry/go-mod-messaging/v4 v4.0.0-dev.18 // indirect
 	github.com/edgexfoundry/go-mod-registry/v4 v4.0.0-dev.4 // indirect
-	github.com/edgexfoundry/go-mod-secrets/v4 v4.0.0-dev.10 // indirect
+	github.com/edgexfoundry/go-mod-secrets/v4 v4.0.0-dev.9 // indirect
 	github.com/fsnotify/fsnotify v1.7.0 // indirect
 	github.com/fullsailor/pkcs7 v0.0.0-20190404230743-d7302db945fa // indirect
 	github.com/fxamacker/cbor/v2 v2.7.0 // indirect
diff --git a/go.sum b/go.sum
index 5996713..7e2ef80 100644
--- a/go.sum
+++ b/go.sum
@@ -70,20 +70,20 @@ github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc h1:U9qPSI2PIWSS1
 github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/eclipse/paho.mqtt.golang v1.5.0 h1:EH+bUVJNgttidWFkLLVKaQPGmkTUfQQqjOsyvMGvD6o=
 github.com/eclipse/paho.mqtt.golang v1.5.0/go.mod h1:du/2qNQVqJf/Sqs4MEL77kR8QTqANF7XU7Fk0aOTAgk=
-github.com/edgexfoundry/device-sdk-go/v4 v4.0.0-dev.25 h1:h31adyPJ+S3YjJcATdKDg3SwE+bLnVQkCzJhDsdv9d0=
-github.com/edgexfoundry/device-sdk-go/v4 v4.0.0-dev.25/go.mod h1:E7fxPSDDLuAnQk1I74m+QBZ/QXay+777x8rJxtKm7Zs=
-github.com/edgexfoundry/go-mod-bootstrap/v4 v4.0.0-dev.28 h1:DmwT+FZlKms2wKdqBw8wAdn4PoMZT5R7TCxAxfyovfg=
-github.com/edgexfoundry/go-mod-bootstrap/v4 v4.0.0-dev.28/go.mod h1:W22AZ7peC6DLN8QKdDhEFaiiL9NFQfk2Hslp/IySqdU=
+github.com/edgexfoundry/device-sdk-go/v4 v4.0.0-dev.24 h1:ltPV5vnpBps6fuojykuUu+slaZnAtOM7mqNRJsOlD90=
+github.com/edgexfoundry/device-sdk-go/v4 v4.0.0-dev.24/go.mod h1:Qlh9FD6LCUrsp3x2b0et0LnMPYGzvXXul9OT0OimeJk=
+github.com/edgexfoundry/go-mod-bootstrap/v4 v4.0.0-dev.27 h1:d1JiYIoFHMHkCeHoYTx4tfRrpPJjVmFAYDUiBfqCOHs=
+github.com/edgexfoundry/go-mod-bootstrap/v4 v4.0.0-dev.27/go.mod h1:JY9Def/1rzes+aBwmI3ge9z+gnPyJdWTP+o+76IrBkg=
 github.com/edgexfoundry/go-mod-configuration/v4 v4.0.0-dev.14 h1:A2LI3YVXGqZS0myTiBrNMFIqIWbH0rNNmLsDPHeI1RM=
 github.com/edgexfoundry/go-mod-configuration/v4 v4.0.0-dev.14/go.mod h1:Sj4PTuZJI5bjQvFh8rz0U1egEu+jkEnlWoHXXUYjgXs=
-github.com/edgexfoundry/go-mod-core-contracts/v4 v4.0.0-dev.28 h1:eli2uheGD7d5qMDFPzNhm3fAEyoDLTgqKWQoDacaF8A=
-github.com/edgexfoundry/go-mod-core-contracts/v4 v4.0.0-dev.28/go.mod h1:D35HIMZkFFy82shKtPYaEL3Nn+ZNEjUjZI1RLn1j23E=
+github.com/edgexfoundry/go-mod-core-contracts/v4 v4.0.0-dev.26 h1:sLzjJnQDukzo6+tRn0coHH+vIMK+L8NL53TWiy5MGbs=
+github.com/edgexfoundry/go-mod-core-contracts/v4 v4.0.0-dev.26/go.mod h1:D35HIMZkFFy82shKtPYaEL3Nn+ZNEjUjZI1RLn1j23E=
 github.com/edgexfoundry/go-mod-messaging/v4 v4.0.0-dev.18 h1:gTaPm8iwdVO0vi8TLuNRYaeNno46Nm6+S04OpubBLlk=
 github.com/edgexfoundry/go-mod-messaging/v4 v4.0.0-dev.18/go.mod h1:h7it/lhC7QhcLKW+KA+D9mCd8Ng3GxT8kSegZMrdEFM=
 github.com/edgexfoundry/go-mod-registry/v4 v4.0.0-dev.4 h1:/IZtXURVZXSKaxHEWVSYHXrNJqoVk2n6OcUR+GmPbgw=
 github.com/edgexfoundry/go-mod-registry/v4 v4.0.0-dev.4/go.mod h1:S5wQ050kYTbZebHqdCC48ojiRghSfnzNLnJLo+FWZH0=
-github.com/edgexfoundry/go-mod-secrets/v4 v4.0.0-dev.10 h1:TU9OBsMeroavoC6Sej8FTTs1scjBhjEHdKrJ5iGHYl8=
-github.com/edgexfoundry/go-mod-secrets/v4 v4.0.0-dev.10/go.mod h1:7L7xJTUayyswdvZNI2GkFZKq7Q33aIn3YyqjBB3L3TI=
+github.com/edgexfoundry/go-mod-secrets/v4 v4.0.0-dev.9 h1:sDiUztFcBnXZ/MeTMj6MRW0vHuI9UY69r4LavedFKRg=
+github.com/edgexfoundry/go-mod-secrets/v4 v4.0.0-dev.9/go.mod h1:SIsFdwhloJEcw4iPuyjidYEoRle4lmerPmTM2IA7fhc=
 github.com/emirpasic/gods v1.18.1 h1:FXtiHYKDGKCW2KzwZKx0iC0PQmdlorYgdFG9jPXJ1Bc=
 github.com/emirpasic/gods v1.18.1/go.mod h1:8tpGGwCnJ5H4r6BWwaV6OrWmMoPhUl5jm/FMNAnJvWQ=
 github.com/envoyproxy/go-control-plane v0.9.0/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
diff --git a/internal/driver/config.go b/internal/driver/config.go
index 204fb04..8716f71 100644
--- a/internal/driver/config.go
+++ b/internal/driver/config.go
@@ -33,9 +33,9 @@ type ConnectionInfo struct {
 
 func (info *ConnectionInfo) String() string {
 	if info.Protocol == ProtocolTCP {
-		return fmt.Sprintf("%s:%s:%d:%d", info.Protocol, info.Address, info.Port, info.UnitID)
+		return fmt.Sprintf("%s:%s:%d", info.Protocol, info.Address, info.Port)
 	}
-	return fmt.Sprintf("%s:%s:%d:%d:%d:%d:%d:%s", info.Protocol, info.Address, info.Port, info.UnitID, info.BaudRate, info.DataBits, info.StopBits, info.Parity)
+	return fmt.Sprintf("%s:%s:%d:%d:%d:%d:%s", info.Protocol, info.Address, info.Port, info.BaudRate, info.DataBits, info.StopBits, info.Parity)
 }
 
 func createConnectionInfo(protocols map[string]models.ProtocolProperties) (info *ConnectionInfo, err error) {
diff --git a/internal/driver/driver.go b/internal/driver/driver.go
index aab27df..0a49a15 100644
--- a/internal/driver/driver.go
+++ b/internal/driver/driver.go
@@ -51,6 +51,13 @@ func (d *Driver) createDeviceClient(info *ConnectionInfo) (DeviceClient, error)
 	return c, nil
 }
 
+func (d *Driver) removeDeviceClient(info *ConnectionInfo) {
+	d.clientMutex.Lock()
+	defer d.clientMutex.Unlock()
+	key := info.String()
+	delete(d.clientMap, key)
+}
+
 func (d *Driver) DisconnectDevice(deviceName string, protocols map[string]models.ProtocolProperties) error {
 	d.Logger.Warn("Driver's DisconnectDevice function didn't implement")
 	return nil
@@ -134,7 +141,8 @@ func (d *Driver) HandleReadCommands(deviceName string, protocols map[string]mode
 	for i, req := range reqs {
 		res, err := handleReadCommandRequest(deviceClient, req)
 		if err != nil {
-			driver.Logger.Errorf("Read command failed. Cmd:%v err:%v \n", req.DeviceResourceName, err)
+			driver.Logger.Errorf("Read command failed, remove the Modbus client from the cache to allow re-establish connection next time. Cmd: %v err:%v", req.DeviceResourceName, err)
+			d.removeDeviceClient(connectionInfo)
 			return responses, err
 		}
 
@@ -193,7 +201,8 @@ func (d *Driver) HandleWriteCommands(deviceName string, protocols map[string]mod
 	for i, req := range reqs {
 		err = handleWriteCommandRequest(deviceClient, req, params[i])
 		if err != nil {
-			d.Logger.Error(err.Error())
+			driver.Logger.Errorf("Write command failed, remove the Modbus client from the cache to allow re-establish connection next time. Cmd: %v err:%v", req.DeviceResourceName, err)
+			d.removeDeviceClient(connectionInfo)
 			break
 		}
 	}


Test patch:
diff --git a/internal/driver/driver_test.go b/internal/driver/driver_test.go
index ca0ae95..7b60b11 100644
--- a/internal/driver/driver_test.go
+++ b/internal/driver/driver_test.go
@@ -75,7 +75,7 @@ func TestDriver_createDeviceClient(t *testing.T) {
 				addressMap:          make(map[string]chan bool),
 				workingAddressCount: make(map[string]int),
 				clientMap: map[string]DeviceClient{
-					"modbus-tcp:172.0.0.1:502:1": &ModbusClient{},
+					"modbus-tcp:172.0.0.1:502": &ModbusClient{},
 				},
 			},
 			args: args{
@@ -102,7 +102,7 @@ func TestDriver_createDeviceClient(t *testing.T) {
 				addressMap:          make(map[string]chan bool),
 				workingAddressCount: make(map[string]int),
 				clientMap: map[string]DeviceClient{
-					"modbus-rtu:172.0.0.1:502:1:9600:8:1:N": &ModbusClient{},
+					"modbus-rtu:172.0.0.1:502:9600:8:1:N": &ModbusClient{},
 				},
 			},
 			args: args{