Wondering if the FAL instruction can be used to increment by +=2 instead of +=1? My array is structured with alternating "data" and "flag" values. If not, I may need to resort to utilizing a FOR loop.
To optimize performance, adjust the value of the 'Length' parameter to half of the array size and incorporate the expression 'the_array[control.POS * 2]' or 'the_array[(control.POS * 2) + 1]' in the FAL instruction. This tweak can enhance efficiency and speed up processing.
drbitboy suggests setting the parameter value of Length to half of the array's length, then utilizing either the expression Code: the_array[control.POS * 2] or the_array[(control.POS * 2) + 1] in the FAL instruction. While this approach seems effective, I discovered that using a structured text for loop offers better readability. A quick JSR implementation resolves the issue. The code snippet to achieve this is as follows: SIZE(Array_Raw, 0, length); FOR i := 0 to (length - 1) by 2 DO Array := Array_Raw * (16.0 / 100.0); END_FOR;
On this forum, everyone tends to have their own favorite topic to discuss, and I am no different. Personally, I believe in steering clear of instructions that are specific to certain brands, such as FAL and similar commands. These commands have become popular due to the belief that they are necessary for ladder logic programming. However, ST commands are much simpler to comprehend, can be used across different processor brands, and do not require extensive research to understand their effects. If someone struggles with ST commands, they may also struggle with LD commands. It is important to include a reference to the 'i' index within the code loop.
Corsair shared his opinion on the forum, stating that everyone has their own preferred topics to discuss, including himself. He believes in staying away from brand-specific instructions, such as FAL and its counterparts, due to their complexity and the perception that they are necessary for ladder programming. In contrast, the simpler ST instruction is easier to comprehend, works independently of processor brands, and does not require extensive research on how the instructions function. If someone struggles with ST, they likely do not fully grasp LD programming either. It is important to ensure that the code within your loop makes reference to the 'i' index. It should be noted that in the case of Rockwell, using STX often entails an additional license fee that not everyone is willing to invest in. Furthermore, many technicians who provide ongoing support for PLC systems often dislike STX and Function Blocks.
Corsair mentioned the importance of incorporating the 'i' index within the loop code. The code snippet below demonstrates the operation on an array involving the 'i' index and a specified formula. Code snippet: SIZE(Array_Raw, 0, length); FOR i := 0 to (length - 1) by 2 DO Array[i] := Array_Raw[i] * (16.0 / 100.0); END_FOR; Regarding Rockwell PLCs, STX licensing can be a point of contention as not everyone is willing to pay for it. Many technicians supporting PLCs tend to dislike STX and Function Blocks once they assume responsibility. Despite this, I personally find Structured Text (ST) to be preferable. It is straightforward and manageable for individuals to work with, especially in simpler tasks. Omitted from the example are additional comments included for clarity.
You can definitely use the FAL (Fetch and Add Long) instruction with an increment of 2 instead of just 1! While many implementations default to incrementing by 1, you could achieve a +=2 effect by just doing the operation twice in a single instruction or using a small adjustment after the first increment. However, if you find it gets too tricky or cumbersome, using a FOR loop to handle it would be a straightforward solution and might enhance readability in your code.
You can't use the FAL instruction to increment by anything other than 1, as it's designed for single increments. However, a FOR loop could definitely be your best bet here—it's pretty straightforward to manage with your alternating "data" and "flag" values. You could just set it to loop through the array with a step of 2, making it efficient while staying clear and readable!
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Answer: - No, the FAL instruction in Logix 5000 does not have a built-in feature to increment by +=2. It only supports incrementing by +=1.
Answer: - In this case, you may need to consider using a FOR loop to manually increment by +=2 in the alternating data and flag array structure.
Answer: - Apart from using a FOR loop, you can explore other programming techniques such as custom logic or utilizing other instructions available in Logix 5000 to achieve the desired incrementing behavior.
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