Device Control

Similar to data collection, after setting up the commands for the device in deviceshifu_configmap.yaml, we can communicate with deviceshifu via HTTP/gRPC, and deviceshifu will convert the commands we send into the form of the protocol supported by the device and send them to the device. After the device receives the command, it can perform the corresponding operation to control the device.

Automated Device Control with Data Collection

Here, we create another virtual device PLC (if you have not tried the PLC device, you can click to view).
```
$ kubectl get pods -n deviceshifu
NAME READY STATUS RESTARTS AGE
deviceshifu-opcua-deployment-765b77cfcf-dnhjh 1/1 Running 0 14m
deviceshifu-plc-deployment-7f96585f7c-6t48g 1/1 Running 0 7m8s
```
At this point we have started two deviceshifu which have each established a connection to a device. We can link the two deviceshifu, that is, when the thermometer temperature exceeds the threshold, set the lowest position of Q area of PLC to 1, and set it back to 0 when the thermometer temperature is below the threshold.

Write the program related to the control device.

package main  

import (  
   "io/ioutil"  
   "log"
   "net/http"
   "strconv"
   "time"
)  

func main() {  
   targetUrl := "http://deviceshifu-thermometer.deviceshifu.svc.cluster.local/read_value"  
   req, _ := http.NewRequest("GET", targetUrl, nil)  
   var isHigh bool  
   for {  
      res, _ := http.DefaultClient.Do(req)  
      Body, _ := ioutil.ReadAll(res.)  
      temperature, _ := strconv.Atoi(string(body))  
      if temperature > 20 && isHigh == false {  
         setPLCBit("1")  
         isHigh = true  
      } else if temperature <= 20 && isHigh == true {  
         setPLCBit("0")  
         isHigh = false  
      }  
      log.Printf("Now remperature is: %d", temperature)  
      Body.Close()  
      Time.Sleep(5 * time.Second)  
   Sleep(5 * time.Second) }  
}  

func setPLCBit(value string) {  
   targetUrl := "http://deviceshifu-plc/sendsinglebit?rootaddress=Q&address=0&start=0&digit=0&value=" + value  
   req, _ := http.NewRequest("GET", targetUrl, nil)  
   res, _ := http.DefaultClient.Do(req)  
   defer res.Body.Close()  
}

For the above program, we can package it as a docker image and load it into the cluster so that it can better communicate with deviceshifu. Create the following Dockerfile file.

# syntax=docker/dockerfile:1  
FROM golang:1.17-alpine  
WORKDIR /app  
COPY go.mod . /  
RUN go mod download  
COPY *.go . /RUN  
RUN go build -o /high-temperature-control-plc 
EXPOSE 11111  
CMD [ "/high-temperature-control-plc" ]

Generate a docker image using the Dockerfile file.

docker build --tag high-temperature-control-plc:v0.0.1

After that we load the docker image into the cluster.

kind load docker-image high-temperature-control-plc:v0.0.1

Run the data acquisition program we wrote.

kubectl run high-temperature-control-plc --image=high-temperature-control-plc:v0.0.1

Also, in order for us to see the values of the PLC device, we load another nginx image.

kubectl run nginx --image=nginx:1.21 -n deviceshifu

8. At this point we have the following `pods`, all in the `Running` state.
```bash
$ kubectl get pods -n deviceshifu
NAME READY STATUS RESTARTS AGE
deviceshifu-plc-deployment-7f96585f7c-87zb4 1/1 Running 0 20m
deviceshifu-thermometer-deployment-7b69b89b88-crwzx 1/1 Running 0 67m
high-temperature-control-plc 1/1 Running 0 8m54s
nginx 1/1 Running 0 61m

The automation device control program we wrote is running, and you can view the data obtained by the program by viewing the live log.

$ kubectl logs high-temperature-control-plc -n deviceshifu -f 
2022/07/07 03:05:07 Now remperature is: 29
2022/07/07 03:05:12 Now remperature is: 10
2022/07/07 03:05:17 Now remperature is: 23
2022/07/07 03:05:22 Now remperature is: 30

Sleep(5 * time.Second)in the program to make it easier to observe the data (to improve the acquisition accuracy, you can turn it down to increase the acquisition frequency). At this point we enter another command into thenginx` container.

kubectl exec -it nginx -n deviceshifu -- bash

When the program gets a temperature above the threshold we get the PLC value via curl.

$ curl "http://deviceshifu-plc/getcontent?rootaddress=Q&address=0&start=0"; echo
0b00000000000000000001

When the program gets a temperature below the threshold we get the PLC value again via curl.

$ curl "http://deviceshifu-plc/getcontent?rootaddress=Q&address=0&start=0"; echo
0b0000000000000000

By now, we have achieved automated control of the PLC device by collecting real-time data from the virtual thermometer.

Automated Device Control with Data Collection​

Automated Device Control with Data Collection