calculate

[drbitboy]

Here is a snippet implementing the same algorithm in ST. How you work this into the SigmaTek/Lasal Class environment is on you. There are some video tutorials that might help; they talk about Servers and Clients, but those seem to be about declaring variables.

  // Inputs:

  //   - current_count (UDINT; current running total of hardware sets completed)

  //   - current_minute (UDINT; range 0-59; minute of hour)

  //     - This could also be a local, temporary variable,

  //       - with a value obtained from .wMinute attribute of SysTimeDate

  // Static (internal data, retains values from scan cycle to scan cycle):

  //   - last_minute (UDINT; range 0-59; minute of hour the last time this function was called)

  //   - oldest_count (UDINT; running total of hardware sets one hour ago)

  //   - count_array (Array[0..59] of UDINT; array of past sixty minutes of running totals

  // Outputs:

  //   - last_hour_average (count of hardware sets completed in the last hour)



  IF current_minute <> last_minute THEN

    last_minute              := current_minute;

    oldest_count             := count_array[last_minute];

    count_array[last_minute] := current_count;

  END_IF;



  last_hour_average := count_array[current_minut] - oldest_count;

 

[Roelofdev]

Thank you. I'm going to see if I can build this up in the Lasal program from Sigmatek

 

[Roelofdev]

What are the raw data?

Does the PLC have the number of products in the current minute?

Or, can the PLC detect individual products?

Here is a notional approach.

FUNCTION hourly_average : UINT
VAR_INPUT
  product_oneshot : BOOLEAN;
VAR_END;
VAR
  stdNow               : SysTimeDate;
  current_wMinute      : UINT;
VAR_STAT
  last_wMinute         : UINT := 0;
  running_total        : UINT := 0;
  current_minute_count : UINT := 0;
  ppm_history          : ARRAY[0..59] OF UINT := { 0, 0, [...], 0};
END_VAR;

  current_wMinute := stdNow.wMinute;
  IF current_wMinute <> last_wMinute THEN
    running_total := running_total - ppm_history[last_wMinute];
    ppm_history[last_minute] := current_minute_count;
    running_total := running_total + ppm_history[last_wMinute];
    last_wMinute := current_wMinute
  END_IF;
  IF product_oneshot THEN
    current_minute_count := current_minute_count + 1;
  END_IF;

  hourly_average := running_total;

END_FUNCTION;

Caveats

• This is a notional approach that knows little about the particular application, but the algorithm is generally sound.
• This takes an 61 minutes of constant uptime to generate the first valid value
• This does not handle downtimes gracefully, but should recover after another 61 minutes of uptime
  • A downtime detector and a flag to reset the running total may be advisable
• To avoid overflow if the product rate is high (>64k/h), UDINTs may be a better choice for the product counts than UINTs
• More effort may be spent coding the assignment of the current_wMinute value than the running_total
  • Using the SysTimeDate function to assign the value of current_wMinute, may be available to the sigmatek PLC
  • Other options:
    • [system time in seconds since some epoch] MOD 60
    • Making current_wMinute a static variable, running a 60s TON timer, and incrementing current_wMinute with rollover after 59[system_time_in seconds_since_some_epoch MOD 60] would be another option.
    • Parsing a time string

I had this code converted by sigmatek. but doesn't quite work. only got the question why there are 2x running_total := running_total + ppm_history[last_wMinute]; is used.

 

[MaxK]

only got the question why there are 2x running_total := running_total + ppm_history[last_wMinute]; is used.

Please show us these lines

I think we'll see the moment when drbitboy starts teaching the alphabet (on this forum)
Let's sing a song: “A-B-C-D-E-F-G-eee…”

 

[drbitboy]

I had this code converted by sigmatek. but doesn't quite work. only got the question why there are 2x running_total := running_total + ppm_history[last_wMinute]; is used.

there are not 2x of those running_total := running_total + ppm_history[last_wMinute] statements.

• The first statement subtracts the oldest minute's data from the running total i.e. subtracts the data from the current minute (0-59) of the previous hour i.e. from an hour ago.
• Then there is a statement that replaces the oldest minute's data (from an hour ago) with the current minute's data of the current hour.
• Then second statement adds the current minute's data (i.e. of the current hour) to the running total.

 

[drbitboy]

Please show us these lines

I think we'll see the moment when drbitboy starts teaching the alphabet (on this forum)
Let's sing a song: “A-B-C-D-E-F-G-eee…”

I think @Roelofdev may be copying my notional code without understanding it. That is not a good idea as my code was only meant as an example to prod them to use a different approach.

Hopefully in this case the code will not result in anyone getting maimed or killed.

Get out the popcorn.

 

[drbitboy]

Please show us these lines

I think we'll see the moment when drbitboy starts teaching the alphabet (on this forum)
Let's sing a song: “A-B-C-D-E-F-G-eee…”

Don't you mean this song?

"0x41-0x42-0x43-0x44-..."

 

[MaxK]

Don't you mean this song?

"0x41-0x42-0x43-0x44-..."

Definitely NOT, because... this information is absolutely inappropriate on a coders forum

Get out the popcorn.

Don't you violating copyrights?