READING ERRORS

[guillermoLeon26]

I am trying to read DINT values, but sometimes these values ​​are incorrect, how can I know if a value I am reading is incorrect?

I want to read values ​​that are stored in the plc. These values ​​are voltage and energy. The voltage values ​​range from 427 to 429, but suddenly they go to 16187392 and again go back to normal. This seems to me a reading error

• Package version: 6.9.0
• Node Version:10.16.3
• Operating System and version: Linux 4.15.0-60-generic #67-Ubuntu x86_64
• Controller Type:1768-L43
• Controller Firmware:20.14

[cmseaton42]

Can you post a snippet of your code?

[guillermoLeon26]

const { Controller, Tag } = require('ethernet-ip')
const fs = require('graceful-fs')

const delay = require('delay')

const PLC = new Controller()

const voltajeLineaAN = new Tag('TDLOW_PQMII.VOL_VAN')
const voltajeLineaBN = new Tag('TDLOW_PQMII.VOL_VBN')
const voltajeLineaCN = new Tag('TDLOW_PQMII.VOL_VCN')

const voltajeFaseAB = new Tag('TDLOW_PQMII.VOL_VAB')
const voltajeFaseBC = new Tag('TDLOW_PQMII.VOL_VBC')
const voltajeFaseCA = new Tag('TDLOW_PQMII.VOL_VCA')

const energiaReal = new Tag('TDLOW_PQMII.ENY_POS_REAL')

console.log('Tablero - TD_LOW_1')

const fecha = new Date().toISOString()
const fila = `VOLTEJE-AB;VOTEJE-BC;VOLTEJE-CA;VOLTAJE-AN;VOLTEJE-BN;VOLTAJE-CN;ENERGIA\n`

fs.appendFileSync(`${__dirname}/archivos/${fecha}.txt`,fila)

PLC.connect('172.30.0.85', 0).then(async () => {
  while (true) {
    try {
      await PLC.readTag(voltajeLineaAN)
      await PLC.readTag(voltajeLineaBN)
      await PLC.readTag(voltajeLineaCN)
      await PLC.readTag(voltajeFaseAB)
      await PLC.readTag(voltajeFaseBC)
      await PLC.readTag(voltajeFaseCA)

      await PLC.readTag(energiaReal)

      let fila = `${voltajeFaseAB.value};${voltajeFaseBC.value};${voltajeFaseCA.value};${voltajeLineaAN.value};${voltajeLineaBN.value};${voltajeLineaCN.value};${energiaReal.value}\n`

      await fs.appendFile(`${__dirname}/archivos/${fecha}.txt`, fila)

      // console.log('Voltaje AN', voltajeLineaAN.value)
      // console.log('Voltaje BN', voltajeLineaBN.value)
      // console.log('Voltaje CN', voltajeLineaCN.value)
      // console.log('Voltaje AB', voltajeFaseAB.value)
      // console.log('Voltaje BC', voltajeFaseBC.value)
      // console.log('Voltaje CA', voltajeFaseCA.value)

      // console.log('Energia Real', energiaReal.value)
    } catch (error) {
      console.log('error', error) 
    }

    await delay(100)
  }
})

[jhenson29]

Have you verified that the values in the PLC aren’t actually doing this?

[guillermoLeon26]

I am comparing the values with those that scada cimplicity throws at me, and that does not happen there.

Maybe it's because the scada cimplicity is already getting information

[cmseaton42]

does the spike happen consistently, say after every 8th scan? or is it random? Also, is simplicity scanning at roughly the same rate you are?

[cmseaton42]

Also, I recommend doing the following as it will limit the number of payloads to the PLC though I don't think it will fix your issue.

const { Controller, Tag, TagGroup } = require("ethernet-ip");
const fs = require("graceful-fs");

const delay = require("delay");

const PLC = new Controller();

const voltajeLineaAN = new Tag("TDLOW_PQMII.VOL_VAN");
const voltajeLineaBN = new Tag("TDLOW_PQMII.VOL_VBN");
const voltajeLineaCN = new Tag("TDLOW_PQMII.VOL_VCN");

const voltajeFaseAB = new Tag("TDLOW_PQMII.VOL_VAB");
const voltajeFaseBC = new Tag("TDLOW_PQMII.VOL_VBC");
const voltajeFaseCA = new Tag("TDLOW_PQMII.VOL_VCA");

const energiaReal = new Tag("TDLOW_PQMII.ENY_POS_REAL");

// Use Tag Group
const group = new TagGroup();
group.add(voltajeLineaAN);
group.add(voltajeLineaBN);
group.add(voltajeLineaCN);
group.add(voltajeFaseAB);
group.add(voltajeFaseBC);
group.add(voltajeFaseCA);
group.add(energiaReal);

console.log("Tablero - TD_LOW_1");

const fecha = new Date().toISOString();
const fila = `VOLTEJE-AB;VOTEJE-BC;VOLTEJE-CA;VOLTAJE-AN;VOLTEJE-BN;VOLTAJE-CN;ENERGIA\n`;

fs.appendFileSync(`${__dirname}/archivos/${fecha}.txt`, fila);

PLC.connect("172.30.0.85", 0).then(async () => {
    while (true) {
        try {
            await PLC.readTagGroup(group);

            let fila = `${voltajeFaseAB.value};${voltajeFaseBC.value};${voltajeFaseCA.value};${
                voltajeLineaAN.value
            };${voltajeLineaBN.value};${voltajeLineaCN.value};${energiaReal.value}\n`;

            await fs.appendFile(`${__dirname}/archivos/${fecha}.txt`, fila);
        } catch (error) {
            console.log("error", error);
        }

        await delay(100);
    }
});

[kyle-github]

The value you get is very suspicious: 16187392r10 = F70000r16. The underlying protocol just reads the bytes in the tag. I am not familiar with how node-ethernet-ip is handling those. JavaScript is not the most fun language in which to handle binary data.

Based on the value in hex, I would be looking at the PLC program or the sensors first.

[guillermoLeon26]

Thanks for answering

The peak occurs randomly and of varying magnitude. And yes I scan at the same speed as simplicity, but when I slow down the scan the same thing happens

I'm going to try another plc with a slower scan speed, I think that plc has problems because by checking I found that there are some memory overflows but I don't know exactly where they are, I'm going to keep investigating

[cmseaton42]

What are the underlying datatypes of the tags? PLC scan time shouldnt matter I dont think but overflowing memory in the PLC could be your issue. If you are using COP or CPS anywhere in your PLC program, then you may be overrunning whatever you are copying data to and writing to the value of your target tag.

[guillermoLeon26]

The incorrect values were produced by a fault in the sensor that is connected to the PLC, now it works perfectly, I am also testing it in another PLC and so far everything works fine

[cmseaton42]

Awesome, glad you got it figured out. I'm gonna go ahead and close this issue. :)