MickeyBob

Hmm, according to the Product Information dialog I'm using Version 8.32J...

I downloaded your code but can't open the project. I get "The CPU of the specified project is not supported by this version. Specify a project corresponding to the CPU." What am I doing wrong? I'm a newbie with GX-Developer so be kind. :)

I guess at this point the only question I have is with regard to the MI command. It sounds like this command really isn't necessary for reading/writing registers. At this point, learning more about the MI command would only satisfy my personal curiosity. If you have found some more information on it, I would like to look at it. Thanks for the help and for being a sounding board!

Ok, I think I have a little better handle on the QQMR and QQIR commands. I'll try to lay it out without confusing me and you When specifying items for the registered I/O table, you specify the area (e.g., HR, WR, DM, etc.), the word address (e.g., 0-9999 for DM), and a bit. For a typical register (all registers except a timer or counter), you can specify a bit from 00 to 15 as you would expect. You can also specify a bit of "CH", which, I surmise, stands for "channel". In this case, the word value is registered (e.g., "@00QQMRDM 0000CH" registers the word value of DM0000). If you use the QQIR command to read a bit, it comes back as a '1' or '0'. If you read a word, it comes back in four hexadecimal digits. But, timers and counters are different. You can specify any two digit number for the bit. No matter what bit you specify, it registers the status bit of the timer/counter. If you specify a bit of "CH" for a timer or counter, both the PV and status bit of the timer/counter are registered (e.g., "@00QQMRTIM 0000CH" registers both the status bit and PV for T0). If you use the QQIR command to read a timer/count "CH" bit, you get back 5 hexadecimal digits. The first digit is either '1' or '0' and corresponds to the timer/counter's status bit. The remaining four digits are the PV word value. Hope I didn't muddy the water further...

Here's the page from the communications manual I was talking about...

Here some more info... I've gotten the QQMR and QQIR commands to work, sorta. I can properly register and read individual bits. For example, the command "@00QQMRHR 000000,HR 000001" registers H0.0 and H0.1. Then when I execute "@00QQIR", the current values are returned as "0,1", assuming that H0.0 is reset and H0.1 is set. However, I haven't figured out how to read word data yet. The format of the QQMR command as shown on page 95 of W342-E1-1 makes reference to the "word data designation" (just below the first line of the command format). I don't understand from this reference how to register a whole word. I also haven't figured out how to read timer/counter PVs and SVs. I have found out from experimentation that I can specify up to 3 bits for a timer/counter (i.e., "@QQMRTIM 000000,TIM 000001,TIM 000002" returns "0,0,0") but don't know to what these map. Trying to read a fourth bit generates a error code 14. Thanks again.

Maybe, I'm confusing you with the term "I/O table". I'm using it in the same sense (I think) as the reference manual, that is, a collection of registers (DM, TIM, EM, IR, etc) that is registered with the CPU using the QQMR command. (which seems to me to be consistent with your last comment) Then, when the QQIR command is issued, the CPU returns the values of the "registered" registers in a comma separated format. I suspect you're thinking of the "I/O table" as the actual PLC I/O configuration table...maybe? Am I understanding this correctly or am I in left-field? Thanks

I had a case of fat fingers or a brain burp (more likely). I meant the MI command instead of the MM command. I have both a hard copy and an electronic copy of the communications manual that I have been referencing but was having trouble putting these particular commands into prospective. I really wasn't sure what a "registered I/O table" meant. Your explanation helped a lot. So if my understanding is correct, I would need to issue the QQMR command to "preregister" the I/O table, the MI command to "correct" or "generate" the I/O table (i.e., have the CPU populate the I/O table with actual values), and then the QQIR command to read the I/O values. To get updates on the same data at a later time, all I would need to do is issue the MI and QQIR commands. Is this correct? Thanks for the help!

I'm implementing a serial HostLink protocol in the open source language Python and have completed just about everything but the MM, QQMR, and QQIR commands. I don't really have a good understanding of what these commands do, what they are used for, and how to use them. Can anyone help me understand these better. Any help will be greatly appreciated. Thanks, MickeyBob P.S. If any one is interested in beta testing my implementation, please let me know.

Thanks!

I have a question about specifying the unit number within a host link (i.e., C-mode) command. According to the manual W342-E1-06 (Communication Command Reference Manual), the unit number is specified in BCD. I'm unsure as to what this really means. Does it simply mean that, for example, unit 15 is specified by the two ASCII characters "1" and "5" (e.g., "@15TSABC07\13") or is it more complicated (e.g., the BCD binary equivalent for decimal 15 is specified in hexadecimal)? Any clarification on this would be greatly appreciated. Thanks, MickeyBob

Rock, Here's a PDF with some figures and a graph that may help clarify your confusion. It gives some concrete examples of how the system works. Let me know if you have any questions. MickeyBob Encoder_Scaling.pdf

I need help figuring out how best to update I/O from a timed interrupt on a CJ1M-CPU21. I have an application where the majority of the time the interrupt is disabled. It is enabled when the value on an analog input exceeds a threshold and is disabled again when the input exceeds a second threshold. I want to refresh the same input value used to enable the interrupt from within the interrupt with the IORF(097) instruction. However, when I enable the interrupt, I immediately get the "Interrupt Task Error Flag" which, according to the Instruction Reference Manual (W340-E3-04), indicates that "IORF(097) was executed in an interrupt task without disabling Special I/O cyclic refreshing." The manual goes on to further say "If cyclic refreshing with the Special I/O Unit isn’t disabled, IORF(097) might be executed during cyclic refreshing resulting in a non-fatal Duplicate Refresh Error and turning ON the Interrupt Task Error Flag (A40213)" I suppose I could disable normal (i.e., cyclic) updating of the input from the setting dialog in CX-Programmer but this would make the input value unavailable when the timed interrupt is disabled. I don't want the interrupt enabled all the time because of the processing overhead. To overcome this problem, I could institute another interrupt that is enabled all the time and it only updates the input. Is this the right way to do this? What are the alternatives? According to the manual, the error is non-fatal. Does this mean the I/O update collision occurred but it didn't really harm/affect the input value? When the error occurs, the error LED on the CPU is turned on and it remains on. Is there a way to reset the error flag in code? Assuming the collision doesn't really mess up the input value, is there a way to "mask" the error? I'll appreciate any insight you guys can provide. Thanks, MickeyBob

Yeah, I thought about that. Call me anal but I hate mixing integers with floats eventhough they are binaryly (new word) the same. I believed I tried other floating-point literals and some worked and other didn't. I can't recall off the top of my head which floats literals worked and which didn't. Thanks for the feedback. MickeyBob

I'm currently using a CJ1M-CPU21. Is it a "version 3" CPU? Is there a way to easily tell? Tx, MickeyBob