Eradicated

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  1. Have you got rotary encoders on these axes as well? If you do then you can use the "Z" signal of the encoder to detect your homing position. Basically drive the motor until you hit the limit switch, then drive the motor the other way until you detect the "Z" signal (i.e. full rotation signal), this will be your know homing position. Obviously if you do not have the encoders you will have to rely on homing sensor (as Mendon mentioned preferably not a typical mechanical one due to the lack of accuracy).
  2. Logic required for product weight selections

    It seems to be a know problem (subset-sum problem), if you search on the Internet you will most likely find a few applicable solutions. Depending on the computational resources you can either try to find the best solution using all the individual weights as inputs, or sort them first and then utilize just a subset of these. I wrote a control program for a multi-head weigher (16 heads) a few years ago, I will have a look and see if I can find it.
  3. Which PLC, HMI, should i choose?

    What type of a motor will you use? Standard 3-phase asynchronous motor, DC motor, servo motor? Will you control it using a relay/contactor or a driver/inverter? In case of positioning, relying on timers is not a good idea, to get any reasonable accuracy you would need an encoder of some kind. To be honest you have not provided any detailed information regarding your application. Tell me what are you trying to achieve, what kind of drives will you use, how complex is the machine, etc. Then we will be able to advise you on the possible solutions.
  4. Allen-Bradley as well as MicroLogix family is something completely new to me. Anyway, I have the following question. I have a MicroLogix 1500 PLC which has to be re-programmed. It has two serial ports, Channel 0 (round-shaped, 8-pin, DIN connector) and Channel 1 (standard DB9 socket). The current software in the PLC makes use of the Modbus Slave mode at the Channel 1. I do not have the dedicated programming cable with round, DIN connector so I would like to program it using a standard DB9-DB9 cable. Now, the problem is - am I able to connect to the PLC using Channel 1? I know that there is a 'default comm parameters' switch, but it only affects the Channel 0. Is there a way to temporarily default the Channel 1 parameters as well? Just for programming? Or maybe I am able to connect to the PLC despite the fact that it is in the Modbus Slave mode on that port? Or do I have to buy the dedicated cable and program the PLC using the Channel 0?
  5. 2 PLC's + 16 HMI's - Ethernet traffic...

    I will briefly describe my control system. I've got the following devices hooked up into a network: 1 x CP1L-EM30DR-D 1 x CJ2-CPU32 16 x HMI (Pro-Face HMI's with Ethernet port). Don't as me why somebody decided to install 16 HMI's into such system, that's not my idea... The devices will communicate in the following manner: CJ2M will query CP1L for data using SEND/RECV commands. Typically about 20-30 words, with temporary increases up to ~500 word queries. Whereas the 16 HMI's will communicate with CJ2M (continuous communication), with approximated traffic of ~30 words per panel (with temporary increases and decreases in queried words count). Now I am worried if the traffic won't be too much for CP1L / CJ2M to handle? Won't CP1L overflow with data when this happy party starts to talk with each other? Did anyone had to deal with such amount of HMI's in the system or similar devices? In general response times are not the most important (200 ms between PLC's is fine). I wonder whether such configuration will handle such traffic. Should I maybe buyj CJ1W-ETN21 card and separate CP1L-CJ2M communication (with separate tunnel via managed switch) and CJ2M-HMI's communication (they would be connected to CJ1W-ETN21 card in such configuration). I would like to cut down the costs, so I would rather not buy the CJ1W card. I would be very grateful for any advice! Here's the image which visualizes the physical connection map for the system: https://dl.dropboxusercontent.com/u/23860146/mrPLC/pConn.JPG
  6. New to NB-Designer

    Maybe I'll just describe the procedure that works for me. I start with adding a new graphics. Then I add required states to the newly created element. Then if I place any element (e.g. bit lamp) on the screen and use the new graphics, the transparency works without any glitches (as an example, yellow background with letter on transparent background). As for your reference, you'll find my .png file with letter A on transparent background here: https://dl.dropboxusercontent.com/u/23860146/mrPLC/letterA.png . Hope that helps.
  7. New to NB-Designer

    You have to use graphics format with native transparency support which is at the same time supported by NB designer. I suggest you use .png graphics. So instead of colored background you use transparent one in .png file.
  8. CJ2M file memory operations

    I've been playing with Omron built-in file functions in CJ2M-CPU32. According to the manuals, I am able to read and write data (with FWRITE and FREAD) and do some other stuff like delete files, create directories (by means of FINS messaging). Now the case is that I want to list all the files in given directory. For example, I have a CompactFlash card installed, with directory \Recipes. In this directory there is an undefined number of .csv files. Assume that I want to make a list of those and display them in HMI. Is it even possible to make such a list in any reasonable manner? Or do I have to know the list of files a priori to access them?
  9. NA series HMI

    There are a few manuals already available on the Web: Hardware User's Manual Software Manual Device Connection Manual Startup Guide
  10. NJ State Machine

    In general I really love the STEP/SNXT functionality in Omron controllers, I just don't understand why other manufacturers do not support something similar, i.e. ladder representation of SFC. That just significantly reduces code responsible for the state machine mechanics. Anyway, I believe that the most popular pattern for implementation of state machines it to program two dependent layers: one layer responsible for the state machine mechanics (i.e. you map the step number to corresponding coil that executes some actions, while also managing transitions from step to step) and the other responsible for the above mentioned actions - i.e. when step coil is active make some movement, turn on the pump etc. Once you get the picture it is quite efficient. On the other hand I've seen some state machines programmed in structured-text FB's (e.g. using case statement), but I'm not really a fan of such solution. Though, maybe somebody else knows something about more efficient ways of programming state machines in PLC-s, also taking into account the new capabilities of NJ-series.
  11. NB Designer Macro

    The problem is that the macro is executed when you press the Number Input component, not when a new value is entered. Thus, the macro ends long before the keypad is displayed. One solution would be to run a cyclic macro when given screen is displayed (let's say every 1 second or so), though that would slow down the HMI a little bit (depending on the macro complexity). The other solution would be to design a custom keypad so that every time you press Enter key the macro would be executed. That would require a custom keypad for every numeric input so I don't think that's a reasonable solution in case of multiple inputs.
  12. I am not really that much into Siemens (I work mainly with Omron PLC's), but from my experience S7-1200 fits for small scale, low cost machines (its' possibilities are quite limited compared to S7-300). If you are willing to use something new you could go for S7-1500 (current replacement for S7-300/S7-400).
  13. I was wondering recently how far can you go when it comes to integration of safety circuitry. Here's an example: I've got a small production line composed of 4 independent machines (system of conveyors, one check-weigher and two processing machines). Now, three of those were provided by an external company, these are stock models incorporating basic safety circuits (mainly E-Stop and several guard doors). Now, imagine I want to have a complete, integrated safety circuit so in case of emergency one does not have to wonder which e-stop button to press and that all the machines will stop immediately. Can I mingle with the safety circuits and develop a single-centralized circuit (obviously under assumption that the person responsible knows what he's doing in accordance with the standards). Or maybe one should avoid at all cost such integration and stick to stopping individual machines with individual e-stop buttons, where the remaining machines will be stopped with standard, non-safety information. I believe there is no single, universal answer to this question, but I would like to ask other experienced people what's their opinion on this subject. I would be grateful for any suggestions as this is not the first time when I'm wondering how far you can, and how far you must go when integrating safety circuitry.
  14. MX2 Speed Control

    Exactly, use the same settings as shown below:
  15. MX2 Speed Control

    Yes, it is possible to control the speed of MX2 inverter via Modbus interface. A001 register is responsible for the frequency source configuration and A002 for run command source configuration. You have to simply change the A001 register to 003 and leave A001 unchanged, this way you will control the speed via Modbus and apply RUN command via terminal block.