Modbus: fix writing bool values (#12972)

provider/modbus.go

@@ -174,12 +174,20 @@ func (m *Modbus) writeFunc() (func(float64) error, error) {
 	return func(val float64) error {
 		val *= m.scale
 
-		switch {
-		case op.FuncCode == gridx.FuncCodeWriteSingleRegister:
+		switch op.FuncCode {
+		case gridx.FuncCodeWriteSingleCoil:
+			var uval uint16
+			if val != 0 {
+				uval = 0xFF00
+			}
+			_, err = m.conn.WriteSingleCoil(op.Addr, uval)
+			return err
+
+		case gridx.FuncCodeWriteSingleRegister:
 			_, err = m.conn.WriteSingleRegister(op.Addr, uint16(val))
 			return err
 
-		case op.FuncCode == gridx.FuncCodeWriteMultipleRegisters:
+		case gridx.FuncCodeWriteMultipleRegisters:
 			b, err := encode(val)
 			if err == nil {
 				_, err = m.conn.WriteMultipleRegisters(op.Addr, op.Length, b)

util/modbus/modbus.go

@@ -182,8 +182,8 @@ func (mb *Connection) ReadCoils(address, quantity uint16) ([]byte, error) {
 	return mb.ReadCoilsWithSlave(mb.slaveID, address, quantity)
 }
 
-func (mb *Connection) WriteSingleCoil(address, quantity uint16) ([]byte, error) {
-	return mb.WriteSingleCoilWithSlave(mb.slaveID, address, quantity)
+func (mb *Connection) WriteSingleCoil(address, value uint16) ([]byte, error) {
+	return mb.WriteSingleCoilWithSlave(mb.slaveID, address, value)
 }
 
 func (mb *Connection) ReadInputRegisters(address, quantity uint16) ([]byte, error) {

util/modbus/register.go

@@ -51,7 +51,7 @@ func (r Register) Length() (uint16, error) {
 	case strings.Contains(enc, "64"):
 		return 4, nil
 	default:
-		return 0, fmt.Errorf("invalid register encoding: %s", enc)
+		return 0, fmt.Errorf("invalid register length: %s", enc)
 	}
 }
 
@@ -171,6 +171,9 @@ func (r Register) EncodeFunc() (func(float64) ([]byte, error), error) {
 	enc := strings.ToLower(r.encoding())
 
 	switch {
+	case strings.HasPrefix(enc, "bool"):
+		fallthrough
+
 	case strings.HasPrefix(enc, "int") || strings.HasPrefix(enc, "uint"):
 		return r.encodeToBytes(func(v float64) uint64 {
 			return uint64(v)