Don't exit on max retries in updateRegisters, except on initial run

README.md

@@ -66,7 +66,7 @@ has been used.
     	Username for HTTP Basic Authentication (default "pingvin")
 ```
 On first run, the daemon generates `~/.config/enervent-ctrl/configuration.yaml` with default values.
-Configuration options are the same as with CLI flags. CLI flags take precedenence over the config file.
+Configuration options are the same as with CLI flags. CLI flags take precedence over the config file.
 - `serial_address:` Path to RS-485 serial device
 - `port:` TCP port for the REST API to listen on
 - `ssl_certificate:` Path to SSL certificate for HTTPS

main.go

@@ -25,7 +25,7 @@ import (
 var static embed.FS
 
 var (
-	version      = "0.1.0"
+	version      = "0.1.1"
 	device       pingvin.Pingvin
 	config       Conf
 	usernamehash [32]byte
@@ -155,7 +155,7 @@ func initDefaultConfig(confpath string) {
 	}
 }
 
-// Read configuration. CLI flags take presedence over configuration file
+// Read configuration. CLI flags take precedence over configuration file
 func configure() {
 	log.Println("Reading configuration")
 	parseConfigFile()

pingvin/pingvin.go

@@ -26,13 +26,14 @@ type pingvinCoil struct {
 
 // unit modbus data
 type Pingvin struct {
-	Coils        []*pingvinCoil
-	Registers    []*pingvinRegister
-	Status       *pingvinStatus
-	buslock      *sync.Mutex
-	handler      *modbus.RTUClientHandler
-	modbusclient modbus.Client
-	Debug        PingvinLogger
+	Coils         []*pingvinCoil
+	Registers     []*pingvinRegister
+	Status        *pingvinStatus
+	buslock       *sync.Mutex
+	handler       *modbus.RTUClientHandler
+	modbusclient  modbus.Client
+	firstReadDone bool
+	Debug         PingvinLogger
 }
 
 // single register data
@@ -310,12 +311,18 @@ func (p *Pingvin) updateRegisters() {
 			if len(results) > 0 {
 				break
 			} else if retries == 4 {
-				log.Fatal("updateRegisters: client.ReadHoldingRegisters: ", err)
+				log.Printf("ERROR: updateRegisters: max retries reached, giving up. client.ReadHoldingRegisters: %v", err)
+				log.Printf("ERROR: error occurred when reading registers %d - %d", k, k+r-1)
+				if !p.firstReadDone {
+					panic("FATAL: Error on initial read")
+				}
+				return
 			} else if err != nil {
 				log.Printf("WARNING: updateRegisters: client.ReadHoldingRegisters attempt %d: %s", retries, err)
 			}
-			time.Sleep(100 * time.Millisecond)
+			time.Sleep(200 * time.Millisecond)
 		}
+		p.firstReadDone = true
 		// The values represent 16 bit integers, but modbus works with bytes
 		// Each even byte of the returned []byte is the 8 MSBs of a new 16-bit
 		// value, so for each even byte in the reponse slice we bitshift the byte