feat: supply string type

cmd/res/devices/modbus.test.devices.toml

@@ -31,3 +31,20 @@
        UnitID = '1'
        Timeout = "5"
        IdleTimeout = "5"
+
+# Pre-define Devices
+[[DeviceList]]
+  Name = 'Modbus TCP Read String'
+  Profile = 'Test.Device.Modbus.String.Profile'
+  Description = 'use for auto read a string value'
+  labels = [ 'modbus TCP' ]
+  [DeviceList.Protocols]
+    [DeviceList.Protocols.modbus-tcp]
+        Address = '0.0.0.0'
+        Port = '1502'
+        UnitID = '1'
+  [[DeviceList.AutoEvents]]
+        Frequency = '20s'
+        OnChange = false
+        Resource = 'ReadString'
+

cmd/res/profiles/modbus.test.device.string.profile.yml

@@ -0,0 +1,41 @@
+name: "Test.Device.Modbus.String.Profile"
+manufacturer: "no manufacturer"
+model: "string value type"
+labels:
+  - "no lable"
+description: "this profile is testing  string value type with read and write"
+
+deviceResources:
+  -
+    name: "StringA"
+    description: "no description"
+    attributes:
+      { primaryTable: "INPUT_REGISTERS", startingAddress: "1", stringRegisterSize: "1"}
+    properties:
+      valueType: "String"
+      readWrite: "R"
+
+  -
+    name: "StringB"
+    description: "no description"
+    attributes:
+      { primaryTable: "HOLDING_REGISTERS", startingAddress: "15", stringRegisterSize: "5"}
+    properties:
+      valueType: "String"
+      readWrite: "RW"
+
+
+
+deviceCommands:
+  -
+    name: "ReadString"
+    readWrite: "R"
+    isHidden: false
+    resourceOperations:
+      - { deviceResource: "StringA"}
+  -
+    name: "WriteString"
+    readWrite: "RW"
+    isHidden: false
+    resourceOperations:
+      - { deviceResource: "StringB" }

internal/driver/constant.go

@@ -36,6 +36,8 @@ const (
 	// RAW_TYPE define binary data type which read from Modbus device
 	RAW_TYPE = "rawType"
 
+	// STRING_REGISTER_SIZE  E.g. "abcd" need 4 bytes as is 2 registers(2 words), so STRING_REGISTER_SIZE=2
+	STRING_REGISTER_SIZE   = "stringRegisterSize"
 	SERVICE_STOP_WAIT_TIME = 1
 )
 
@@ -58,5 +60,6 @@ var ValueTypeBitCountMap = map[string]uint16{
 	common.ValueTypeFloat32: 32,
 	common.ValueTypeFloat64: 64,
 
-	common.ValueTypeBool: 1,
+	common.ValueTypeBool:   1,
+	common.ValueTypeString: 16,
 }

internal/driver/deviceclient.go

@@ -63,7 +63,17 @@ func createCommandInfo(req *models.CommandRequest) (*CommandInfo, error) {
 			return nil, err
 		}
 	}
-	length := calculateAddressLength(primaryTable, rawType)
+	var length uint16
+	if req.Type == common.ValueTypeString {
+		length, err = castStartingAddress(req.Attributes[STRING_REGISTER_SIZE])
+		if err != nil {
+			return nil, err
+		} else if (length > 123) || (length < 1) {
+			return nil, errors.NewCommonEdgeX(errors.KindLimitExceeded, fmt.Sprintf("register size should be within the range of 1~123, get %v.", length), nil)
+		}
+	} else {
+		length = calculateAddressLength(primaryTable, rawType)
+	}
 
 	var isByteSwap = false
 	if _, ok := req.Attributes[IS_BYTE_SWAP]; ok {
@@ -157,6 +167,8 @@ func TransformDataBytesToResult(req *models.CommandRequest, dataBytes []byte, co
 		if (dataBytes[0] & 1) > 0 {
 			res = true
 		}
+	case common.ValueTypeString:
+		res = string(dataBytes)
 	default:
 		return nil, fmt.Errorf("return result fail, none supported value type: %v", commandInfo.ValueType)
 	}
@@ -195,7 +207,7 @@ func TransformCommandValueToDataBytes(commandInfo *CommandInfo, value *models.Co
 		dataBytes = swap32BitDataBytes(dataBytes, commandInfo.IsByteSwap, commandInfo.IsWordSwap)
 	}
 
-	// Cast value according to the rawType, this feature only converts float value to integer 32bit value
+	// Cast value according to the rawType, this feature converts float value to integer 32bit value
 	if commandInfo.ValueType == common.ValueTypeFloat32 {
 		val, edgexErr := value.Float32Value()
 		if edgexErr != nil {
@@ -228,8 +240,21 @@ func TransformCommandValueToDataBytes(commandInfo *CommandInfo, value *models.Co
 				return dataBytes, err
 			}
 		}
+	} else if commandInfo.ValueType == common.ValueTypeString {
+		// Cast value of string type
+		oriStr := value.ValueToString()
+		tempBytes := []byte(oriStr)
+		bytesL := len(tempBytes)
+		oriByteL := int(commandInfo.Length * 2)
+		if bytesL < oriByteL {
+			less := make([]byte, oriByteL-bytesL)
+			dataBytes = append(tempBytes, less...)
+		} else if bytesL > oriByteL {
+			dataBytes = tempBytes[:oriByteL]
+		} else {
+			dataBytes = []byte(oriStr)
+		}
 	}
-
 	driver.Logger.Debugf("Transfer CommandValue to dataBytes for write command, %v, %v", commandInfo.ValueType, dataBytes)
 	return dataBytes, err
 }