panic mode

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Posts posted by panic mode

  4. Posted

    you need to define what is that you really need, stop moving the goal posts. first you wanted an integer, then floating point, then fixed point.

    what are you using value for?

    if it is display, then integer is fine. you can specify decimal place by formatting your HMI object

    if you are looking at value to control the process, floating point (95.000002) is fine

    but floating point values (real type) cannot accurately represent any number.... there is going to be rounding.

    so the other option is to keep it in string format...

    what is it going to be?

     

  8. Posted

    MyInt = 0
    MyInt = MyInt * 10 + (sHPA[0] - 48 )
    MyInt = MyInt * 10 + (sHPA[1] - 48 )
    MyInt = MyInt * 10 + (sHPA[2] - 48 )
    MyInt = MyInt * 10 + (sHPA[3] - 48 )

     

    or

    MyInt =  (sHPA[0] - 48 )
    MyInt = MyInt * 10 + (sHPA[1] - 48 )
    MyInt = MyInt * 10 + (sHPA[2] - 48 )
    MyInt = MyInt * 10 + (sHPA[3] - 48 )

     

    48 is decimal value for 0x30

     

  10. Posted

    it is just like any other PLC. programming software resides on a development station (your laptop). you simply deploy project to a target PLC which has own firmware and license.

    if you do not have physical PLC and wish to learn how to use TwinCat, you can use local runtime. it is an equivalent of a PLC but runs on your own machine. it too needs license but for local runtime, you simply create new temporary license yourself whenever needed.

  13. Posted

    the key problem here is very low baud rate. crank that to 115.2kbps or even 230.4kbps and you will get 10x or 20x higher performance. 

    another thing to consider is the actual process values. temperature changes are slow but pressure changes can be very fast. you could modify your code to read temperatures less frequently (say 10x less frequent). that could give you further bust. 

  14. Posted

    hmm... that sounds awfully slow... what hardware? are you using Ethernet or serial? if serial what baud rate and how many registers we are talking about?

    for performance it would be prudent to map all the monitored data into consecutive registers and read them all at once. also it would be good to make sure your target device is able to deal with the required transfer rates. 

    in couple of recent projects i was using Ethernet to continuously read some 80 registers and write another 30. I chose to update every 100ms but as i recall ratcheting this to 10ms was not an problem at all.

     

  15. Posted

    i am not aware of direct replacement but one can compose data in a number of different ways. one of them is to use mask and shift instructions. for more convoluted arrangements it is probably easier and more readable to simply pack things bit by bit using contacts and coils.

    MOV D4 K4M0 ; copy 16 bits from D4 to M0..M15

    then use LD/OUT to remap the M bits to some other place (M100..M115 for example) with order you like

    and move it back using

    MOV K4M100 D5

    depending on particular CPU version other options may also exist.

    and if you like, just make own function that duplicates BTD exactly

     

     

  18. Posted

    i have twincat3 running on my current machine. personally i love freedom and plethora of programming options this system offers. just for learning one can simply download and install TwinCat3, without getting PLC or iPC  because it comes with runtime. however if you can, it is always better to get the real hardware. 

    as for messing things up, things got better over the years but there are still glitches. one of the problems is that using shared CPU core for runtime is likely to conflict with any other virtualization platform (vmware, virtual box...). workaround is to assign dedicated CPU core to runtime. your Windows will have one less core but this tends to solve some of the conflicts (but not all). i use bunch of VMs for other things and... usually couple of them are running. Since TwinCat is installed on this machine, i still get occasional crash. In worst case PC got locked up  and all one can do is hold power button to force shutdown. Did not get that since assigning one of CPU cores to RT. also i try to stop RT when not in use. 

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  20. Posted

    if you do want to write words (MW...) and set/reset single bit you need to manipulate the bit in the word and then write entire word.

    if you want to ensure there is no corruption, you should first read the word, manipulate the bit of interest, then write the word back.

    but first of all let's make things clear - you should not use same register for R/W access as this is too long and complicated (read>manipulate>write back) and there is always a chance of getting things out of sync. this is because value that you read could be out of date by the time you write new value back, some of bits could already be modified (in the PLC) so your write back attempt would overwrite them and thus create corruption.

    it is a MUCH better approach to simply choose a range of memory locations (such as register) that you only read and choose another range that you only write. once the value is transferred, you may evaluate it at received end - no need to write back. 

    that is of course if you want to reduce your communication to single read and single write... 

    but if you do not wish to parse received data, then instead of reading just one range of memory locations (such as registers), read two or three or more... one could be bits/coils, another could be bytes, another could be words...

    same goes for writing values back to PLC. instead of writing one range of memory locations, just use two or more writes. again, one could be some range or bits/coils, another could be bytes, another could be words...

     

  21. Posted

    well solution is to use all resources at your disposal that Easymodbus offers. and it has plenty...

    on the right side is EasyModbusTCP Server Simulator. it is a great substitute for PLC when doing testing.

    on the left side is corresponding client which has ability to read/write anything including single coils...

    so, all you need to do is try it and look inside the code how things work. 

    EasyModbus.png

  24. Posted

    1 hour ago, Zamora said:

    The QD77MS4 Module is mounted in Base Slot #3, so I use U2\G800, U2\G1500, etc... to Read/Write from it. 

    so why do you think that U2\xxx should work? and what was the U?\... you tried when module was in slot 1?

    that number "2" in U2 is not a 'slot number'... it is a base address which is begin of I/O address for that slot.

    what are the modules in slots before Slot#2? depending on how much I/O they consume will determine base address of next module.

    if you put the module next to CPU, base address should be 0, so U0\G800 etc.

    suppose slot1 is a card with 32inputs. thay means they will be X0...X1F

    so next slot (slot2) will start with X20. if module there is 16inputs, they will be X20..X2F.

    then next module (slot 3) will start with X30.

    base address is obtained by removing "X" and the last digit. so in this case module in slot 3 would have base address 3 ("X0030" after removing X and last 0 becomes 003 or just 3). so you would need to use U3\G800 instead of U2\G800.

     

    if module in slot 5 uses inputs X0320..X033F then base address would be 032  and not 4 

     

     

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