How to save value of integer variable in TwinCat3?

Question

I have a program in TwinCat where 5 integer variables are being updated every 10 seconds to represent the state of 5 pumps. I want to save these values that are being generated into either a textfile or CSV file that I can later extract from the PLC. Code below:

IF toninPumpPulse.Q THEN
    rinPump1RPM := (inPump1Count/6)*6; //Pulse sample for 10 seconds. 6 pulses = 1 round.
    inPump1Count := 0; //Reset counter for next 10 second sample
    rinPump2RPM := (inPump2Count/6)*6; //Pulse sample for 10 seconds. 6 pulses = 1 round.
    inPump2Count := 0; //Reset counter for next 10 second sample
    rinPump3RPM := (inPump3Count/6)*6; //Pulse sample for 10 seconds. 6 pulses = 1 round.
    inPump3Count := 0; //Reset counter for next 10 second sample
    rinPump4RPM := (inPump4Count/6)*6; //Pulse sample for 10 seconds. 6 pulses = 1 round.
    inPump4Count := 0; //Reset counter for next 10 second sample
    rinPump5RPM := (inPump5Count/6)*6; //Pulse sample for 10 seconds. 6 pulses = 1 round.
    inPump5Count := 0; //Reset counter for next 10 second sample

I am looking to have a new CSV file be created and then populated with the variable values. I am pretty inexperienced in TwinCat and reading the Beckhoff website is not exactly helping as well.

Answer 1

You want to use a combination of several function blocks:

• FB_FileOpen
• FB_FilePuts
• FB_FileClose

All documentation you need + example code is already available on the Beckhoff infosys for this purpose:

https://infosys.beckhoff.com/english.php?content=../content/1033/tcplclibutilities/html/tcplclibutilities_csv_sample.htm&id=

Also see this on how to write files in general: TwinCAT 3: Write to File

Answer 2

The open source logging library TcLog may help you. It provides extended logging functionalities to the file system.

I wrote a blog post introducing it, you can also download a precompiled library there.

This is how you would use it in your case:

First, define a static logger instance of type TcLogCore that contains the configuration:

VAR
  CoreLogger : TcLogCore;
END_VAR

CoreLogger
 .MinimumLevel(E_LogLevel.Warning)
 .WriteToFile('c:\logs\', 'pumpValues.csv')
 .RunLogger();

Next, define a logger TcLog that actually logs the messages:

VAR
  Logger : TcLog;
END_VAR

You can use that logger to generate log messages like this:

Logger
.OnCondition(toninPumpPulse.Q)
.AppendAny(rinPump1RPM)
.AppendString(',')
.AppendAny(rinPump2RPM)
.AppendString(',')
.AppendAny(rinPump3RPM)
.AppendString(',')
.AppendAny(rinPump4RPM)
.AppendString(',')
.AppendAny(rinPump5RPM)
.ToCustomFormat('');

Make sure, toninPumpPulse.Q is only true for one cycle, otherwise you will generate a load of messages. Have a look at logging on rising/falling edges as well.

Since the logger is implemented as Singleton, you can use it anywhere in your program and it will automatically use the configuration of TcLogCore.

There are more options in the library, like setting a rolling interval for the log files or automatic deletion of old files that may be useful to you.