In my RSLogix5000 programming, I am looking to analyze a string for a specific character and utilize its position to trigger a solenoid valve. The string has a format like this: SWV01T0000000001B00OP008OOOOOOOO$r. I am focused on examining the section highlighted in red (the letter O, not zeros). I am particularly interested in locating any instances of the letter F within this section for error detection purposes. Multiple occurrences of the letter F may be present in the string, and I need to identify each one for tracking purposes. While I have considered using the FSC (File Search and Compare) instruction for this task, I have not yet achieved success. I am seeking guidance from anyone who has experience with a similar task and is willing to point me in the right direction.
To streamline the process, I would recommend starting with a MID command to extract the O's and F's from the string and transfer those characters to a separate string. This will allow for easier comparison of each character. While it is technically possible to achieve this without the MID command, it helps to organize the code. For example, if the string is named FirstString, you can use the following code: MID FirstString 8 25 ValveStringEQU ValveString.DATA[0] FString.DATA[0] OTE Valve1EQU ValveString.DATA[1] FString.DATA[0] OTE Valve2...EQU ValveString.DATA[7] FString.DATA[0] OTE Valve7 Create FString as a tag and initialize it with "F" to make monitoring for changes easier. Although the MID command is optional, it simplifies the process and creates a convenient tag for monitoring.
To create array tags, use the following structured text: Fpos_array[StringLen] and Opos_Array[StringLen]. Initialize F_Pointer and O_Pointer to 0. Clear the arrays by looping through Fpos_Array and Opos_Array and setting each element to 0. Next, iterate through the string to search for required characters ('F' and 'O'). If a character is found, store its position in the corresponding array. This code populates the arrays with the positions of 'F' and 'O' characters. It is effective, although syntax errors may occur due to using multiple text-based languages.
Thank you cbuysse for your suggestion. I had considered that approach but I am concerned about the potential expansion of this string in future machines, where the 8 characters I am analyzing could potentially increase to 48 or more. Therefore, I am seeking a more efficient method rather than writing code for each element individually. I have successfully utilized the FSC instruction to search the string, but now I am faced with the challenge of identifying each position within it. Once I make more progress towards my objective, I will share the code. Thank you dr_cronik for your input. I have not explored using Structured Text much, but I will give it a try later today to see what results I can achieve.
Have you considered using the FIND function? This tool will help you pinpoint the initial position.
dmargineau inquired about the function "FIND" for locating the starting position in a string. However, I encountered an issue where FIND only identifies the first occurrence of the letter "F", whereas I need to find all instances of "F" in the string.
It sounds like you're on the right track using the FSC instruction, but it can be a bit tricky with strings. To better identify all occurrences of the letter 'F' within your specific section, consider breaking down your string into substrings that isolate the relevant portion. You could set up a loop that checks each character in that section against 'F' and uses a counter to keep track of how many times it appears. Also, don’t forget to validate your string length to avoid any out-of-bounds errors. If you're still having trouble, it might be helpful to share your current logic so others can provide more specific advice based on what you've already tried. Good luck!
It sounds like you’re on the right track with wanting to use the FSC instruction, but it can be a bit tricky if you're not fully familiar with the string manipulation in RSLogix5000. One alternative you might consider is using a combination of the LEN (Length) and SUB (Substring) instructions to isolate the relevant section of your string first. Once you have that portion, you can loop through it character by character and use a counter to track the occurrences of 'F'. It might also help to set some flags when you find a match so that you can trigger your solenoid valve accordingly. Good luck, and feel free to share your progress!
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Answer: - To find and track specific characters in a string in RSLogix5000, you can utilize instructions like FSC (File Search and Compare) to search for the desired character within the string. You may need to consider the position of the character within the string to trigger specific actions, such as activating a solenoid valve.
Answer: - To locate multiple occurrences of a specific character within a string, you can iterate through the string using a loop and search for the desired character at each position. You can keep track of the positions where the character is found for error detection and tracking purposes.
Answer: - When differentiating between the letter 'O' and zeros in a string, you can specify the character specifically as 'O' in your search criteria to avoid confusion with zeros. By focusing on the exact character 'O' within the string, you can accurately locate instances of the letter 'F' for error detection within the desired section of the string.
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