#9 Function to update all coil values

enervent-ctrl-go/main.go

@@ -2,16 +2,14 @@ package main
 
 import (
 	"fmt"
-	"log"
-	"time"
 
 	"github.com/0ranki/enervent-ctrl/enervent-ctrl-go/pingvinKL"
 )
 
 func main() {
-	log.Println(time.Now())
 	pingvin := pingvinKL.New()
-	log.Println(time.Now())
+	pingvin.Update()
-	fmt.Println(pingvin.ReadCoil(40))
+	for i := 0; i < len(pingvin.Coils); i++ {
-	log.Println(time.Now())
+		fmt.Println(pingvin.Coils[i].Symbol, pingvin.Coils[i].Value, pingvin.Coils[i].Description)
+	}
 }

enervent-ctrl-go/pingvinKL/pingvinKL.go

@@ -49,7 +49,7 @@ func readCsvLines(file string) [][]string {
 	return data
 }
 
-// Configure the modbus client on creation
+// Configure the modbus parameters
 func (p PingvinKL) getHandler() *modbus.RTUClientHandler {
 	// TODO: read configuration from file, hardcoded for now
 	handler := modbus.NewRTUClientHandler("/dev/ttyS0")
@@ -58,25 +58,52 @@ func (p PingvinKL) getHandler() *modbus.RTUClientHandler {
 	handler.Parity = "N"
 	handler.StopBits = 1
 	handler.SlaveId = 1
-	handler.Timeout = 200 * time.Millisecond
+	handler.Timeout = 1500 * time.Millisecond
 	return handler
 }
 
 func (p PingvinKL) Update() {
-	// coildata, err := p.Client.ReadCoils(0, len(p.Coils))
+	handler := p.getHandler()
+	err := handler.Connect()
+	if err != nil {
+		log.Fatal("Update: handler.Connect: ", err)
+	}
+	defer handler.Close()
+	client := modbus.NewClient(handler)
+	results, err := client.ReadCoils(0, uint16(len(p.Coils)))
+	if err != nil {
+		log.Fatal("Update: client.ReadCoils:", err)
+	}
+	// modbus.ReadCoils returns a byte array, with the first byte's bits representing coil values 0-7,
+	// second byte coils 8-15 etc.
+	// Within each byte, LSB represents the lowest n coil while MSB is the highest
+	// e.g. reading the first 8 coils might return a byte array of length 1, with the following:
+	// [4], which is 00000100, meaning all other coils are 0 except coil #2 (3rd coil)
+	//
+	k := 0                              // pingvinCoil index
+	for i := 0; i < len(results); i++ { // loop through the byte array
+		for j := 0; j < 8; j++ {
+			// Here we loop through each bit in the byte, shifting right
+			// and checking if the LSB after the shift is 1 with a bitwise AND
+			// A coil value of 1 means on/true/yes, so == 1 returns the bool value
+			// for each coil
+			p.Coils[k].Value = (results[i] >> j & 0x1) == 1
+			k++
+		}
+	}
 }
 
 func (p PingvinKL) ReadCoil(n uint16) []byte {
 	handler := p.getHandler()
 	err := handler.Connect()
 	if err != nil {
-		log.Fatal("ReadCoil1: ", err)
+		log.Fatal("ReadCoil: handler.Connect: ", err)
 	}
 	defer handler.Close()
 	client := modbus.NewClient(handler)
 	results, err := client.ReadCoils(n, 1)
 	if err != nil {
-		log.Fatal("ReadCoil2: ", err)
+		log.Fatal("ReadCoil: client.ReadCoils", err)
 	}
 	return results
 }