andre_teprom

Hi there!   Once there is no 8-bits native type available for this platform (instead, only single bit, 16 and 32 bits are supported), I would like know if anybody here has some Function Block (FB) that do this job, or rather, if there is a trick to do that. I could not realize a simple way so far. The problem that I'm facing now is that in order to handle the TCP protocol, it is necessary to handle byte per byte.   Thanks in advance, Andre. [EDIT]   I found instructions WTOB,  SHL and  SHR which seems candidates to be used....I'll make experiments with it.

@kaare_t: Thanks for the comments, I did not really make it very clear when I was mentioning just "performance" with no additional details. I was concerned on the processing power per second, or something like that. The fact is that the program on which I am working brings together a huge amount of tasks, which are not only interlocking, but rather huge processing in realtime at a high rate. To make things worse, I wanted to gather some tasks that currently run on another PLC so as to have everything on a single hardware platform. Unfortunately, for the initial analysis done so far, this would not be possible at first since at least the main PLC is now running somewhat beyond 50% of its runtime. As for the manufacturer I am currently using, due to NDA issues I can not disclose this information, the only thing that I can share is that it core is based on the X86 architecture and it has built in floating point ALU, which is nice for REAL number calculations.  but this should not matter on the subject in question. Anyway, from all your inputs it is becoming more and mode clear that what I wanted does not exist, and therefore I will have to compare by other criteria the processing capacity of each PLC.

As for your recommendation to ask for such an advice to the manufacturer of the products I currently use, I don't think they would kindly give it, as they have their own metrics whose criteria for computing it are not disclosed; moreover, I could not find anywhere else their grades, therefore it would not be helpful to use a proprietary scale parameters to compare with products from other manufacturers.  As for the usefulness to go to that event, as stated above, seeking for news is just 'one' of the reasons, therefore this is not a waste of money and time, otherwise there would be no reason for manufacturers to invest in events like those, but this is getting off topic. Anyway I was expecting insights with a slightly more technical approach rather than sarcastic. By the way, although relatively new on the PLC world, I have more than 20 years with programming and design of embedded systems, so good programming practices are already present on what I do. Thanks.

As I am relatively new to the PLC world (I worked with only one brand), and I will probably go to "Hannover Messe 2019", I would like to be able to quantitatively evaluate the performance of other PLCs compared to the one I currently use. One of the reasons for my trip will be to analyze other up to date available solutions. I-m not concerned about costs (software licensing, hardware price, etc ...), I'm more interested to focus on the performance aspects. Is there any standardized or common use metrics for performance comparison of PLCs from different manufacturers ?

Just giving a feedback, I was able to determine the likely reason for the variable being inserted into the program with no apparent reason; After I added another input card into the set, I noticed that a variable associated with an HW input of the new card was being linked to a low priority task. Only after I put this variable in the same way above (without reading or writing to it) inside a PRG file, the compiler assigned the variable to the highest priority task, instead. I believe that the case mentioned in post #1 above was a mere forgetting of the previous programmer, whose null allocation should have been performed only to him be able to debug the its working by checking its operation throught the IDE itself...just guessing.

Once I also did not see anything similar anywhere, I was guessing it could be just to assynchronously force the update of the variable value before the next Task() iteration, but I'm happy that I'm not the only one which found this somewhat weird. Thanks for your note.

Hello, The program I'm working on, which was written by another professional who does not work in the company anymore. My doubts lie in the programming language itself, namely IEC-61131-3 (ST). In a section of the program (PRG) code, a BOOL variable appears without any assignment or evaluation, only itself followed by a semicolon, as this: PLC_Ok; I did not understand what the purpose of this, could anyone give an insight ? Thanks in advance.