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  1. CPT instructions on a PLC-5/40

    I'm working to fix/improve the functioning of a program running on an a PLC5/40E.  I think high Scan Times are a big problem with this current program.  ((Backstory:  someone added some quasi motion control, and it sort of worked for a while.  Now that it's broken, the operators of this machine want it back. ))  I'll keep my question simple, PLC5's are new to me: There are 36 rungs with CPT instructions as the sole output, a third of these instruction are executed every scan.  I'm going to replace them with MOV instructions. My question is, is there any sneaky PLC5 reason to do a CPT instead of a MOV?  Is there a better way to do this? The CPT instructions that execute move integer values to a data file used by the HMI to control the coloration of touchscreen buttons.   Thank you for your time. PS: I'm new-ish to this forum, please feel free to let me know if my question was asked correctly or not.
  2. The CC-Link system on a machine has been intermittently dropping out.  Normally the Link Scan Time runs at a solid 87ms.  When the system "drops out", the link scan time will increase.  Sometimes double, triple, or go up 10x. It happens when the machine is running or when it sits idle. There are 33 stations on the network.  The same stations do not always fault but sometimes all of the stations will fault at once (as seen in the attachment pictures.) We have changed the main QJ61BT11N, the processor, the Q62N power supply, the main backplane (base unit), all cards on the main backplane.  Is it possible for one station or one of the cables to create a network wide problem?  Any ideas thrown at us would be appreciated. 
  3. So I have done quite a bit of googling and i even reached out to our integrator but i am having a nuisance fault of "Watchdog Fault" Caused by periodic task overlap. The task is scheduled to start again before it is finished. I added all of the Programs in this task MAX scan time and it only came out to 102 ms. the task is scheduled for every 100 ms. The watchdog is set at 500 ms. The task is currently running at 146-148 ms and i confirmed this using a TON instruction at the end of the task followed by a reset. What can i do to get this down?? What would be the best practice? Move programs into another task? Make the task continuous? What would happen if i did make it continuous? I tried setting the task to 150 ms and the controller DID NOT like that. I was barely able to get back on line with it to change it back to 100 ms. CPU usage is at 91% and this task accounts for around 50% of that. Thank you all in advance for your help.
  4. Hi everybody,For a while I’ve been wondering, in every plc forum where the use of loops come to discussion I find most people answering that it’s best to stay away from them and that there are better, easier and mostly less scan time demanding solutions out there. Why is that?In my experience they’re the next best thing.Why would referencing data from an array of 40 Dwords using a FOR X:= 0 TO 40 DO loop be any more scan time demanding then the PLC scanning through 40 rungs of statments?Just curious if I’m missing something here. Cheers
  5. OK,  I have a program in a Control Logix 5561 controller(ver. 19.52) that every time we go online with it, the communication between the PLC and the PC running RS5000 is so slow you cannot navigate the program efficiently. I am new to this facility but I noticed the programmer used 20 different periodic tasks to organize their program, mostly running at 30ms intervals. several are set to 10ms and some are even set to 3ms. I have gone through and found out that the short interval tasks have been overlapped 10's of millions of times, and the combined total of all scan times is over 160ms. I have a strong feeling this could be causing our comms bog down and possibly other erratic behavior but would like a second opinion. This machine has 2 indexing dials, with work stations that do work between indexes, Pick and Place operations, etc.  Is there even a need to be running these with periodic tasks? All thoughts are appreciated. Thank you
  6. Hi, I'm a long time lurker and would like to start by saying thanks for all the help over the years, much appreciated!  This is my first post, please be gentle. I'm working through a large project with an L83 (V28) including 75 EIP nodes & 5 servos.  We have a need for quick real-time response of 2 cameras during a quick servo move (taking several pictures).  I've broken my program up into a few event driven tasks (allowing me to chose the execution time interval (5 to 8 ms for more important tasks and 20 ms for less important tasks, etc.)), along with these I have 2 periodic tasks: 1 for my HMIs & faults running every 30ms and 1 for this quick real-time response camera situation running at .5ms which contains my camera and servo logic.  Everything is running well and seems responsive and repeatable enough, but I am now adding the second half of the logic which will essentially double everything (2 up system).  This has made me consider the best structure approach: Is it better to have a few larger routines within a few larger tasks or better to have more smaller tasks containing an abundance of smaller routines or some other different mix? Thanks, JD43    
  7. Hi Gentlemen, I ran into a Sixnet RTU job recently. I noticed that there's no 1st scan bit! Don't know how to get the run status or the 1st scan bit. Maybe I am not looking in the right place. Is there a way around this? Maybe this is a stupid question but shall appreciate any help. Thanks for looking in.
  8. My project is converting a Quatum Modicon to a Control Logix. We took the Modicon Logic ran it thru a Rockwell converter and created the Control Logix Logic. This was nothing complicated but a large file. In Modicon you have a Memory retentive bit -- (M). This converted to a Latch (OTL) in the Control Logix, we decided to place a coil OTE in Parallel with the Latch so we could unlatch on the rung going false. The memory retentive coil is there to hold memory on power cycle if it ever happened. So.... The question is Unlatch below The latch, or above Consider left a representive of converted logic in the AB. Logic a bit more complicated. A B C lL. U --||--|||--|/|--(OTL)--(OTE). L |. . --||-----|. U. L ----||--------------------(OTU)