Need opinions

[frank.raymond 0]

I am looking for a small handheld HMI where I can change fixed DM locations and their values. I need to monitor six DM registers in ASCII via a CJ cpu serial comm port. When I am not updating the DM locations the comm port will be connected to a barcode scanner thus I'll unplug and plug each device as needed. The logic is not an issue. What are your opinions on a small HMI handheld? Thanks...

[MPM 1]

Hi, OMRON NSH5 handheld terminal. Regards, MPM

[scottmurphy 1]

What PLC are you using? I am assuming that your barcode scanner is a standard serial, and you serial port is configured for RS232C? This may also affect your device selection?

[frank.raymond 0]

CJ1M

[Eric Apperley 0]

As Scott pointed out we have done exactly that on a PDA using Bluetooth (plus other functions). The application program for the Windows CE PDA was written in .NET and communicated via a virtual serial port under Bluetooth using both Hostlink and FINS protocols. The application was written for an OMRON customer however the project was cancelled so it never proceeded to completion, however extraction of data from the PLC DM Memory was successfully demonstrated to the Customer by the local OMRON rep. I'll try to give you a balanced perspective. Some thoughts, although I'll probably turn you off the concept ... Advantages of PDA Approach: ---------------------------------- a) The PDA user interface is clearly better suited to a non-technical user (not sure whether this is an issue in your application if you will be the one using it). Basically its a slightly crippled Windows user interface but easy to assimilate for most users these days. b) PDA + Promi-SD Bluetooth Adapter cost may be cheaper than the OMRON handheld? Not sure on this ... PDA's have come down in price and up in capability for the lower-end models. c) The PDA can be used for other tasks, its not dedicated to just communicating with the PLC. However, this might be a disadvantage for users who like to fiddle with things ... d) Using Bluetooth means you won't damage/wear out the connector on the PLC over time however you'd either need a Bluetooth adapter on the scanner too plus some mechanism to tell the PLC what device to expect on the serial port OR perhaps use the Peripheral Port for the scanner? The PDA is quick to "connect" - no cables to plug/unplug, just tap on a button on the display. e) Can be used remotely from the device - I've tested in commercial buildings up to 10m without issues, however range will be reduced somewhat in an electrically-noisy industrial environment. Disadvantages of PDA Approach: -------------------------------------- a) Limited user interface available on the PDA - small amount of "real estate" (screen) therefore difficult to display much. Also no keyboard per se (although some PDAs do have tiny keypads incorporated). Relies on tapping objects displayed on the screen or use of the "SIP" (soft input keypad) to enter values. "Do-able" but not as nice as having a decent keypad. b) PDA's are not ruggedised, therefore a PDA may not be suitable for the environment (depends on your application and the class of user). c) The PDA may be cost effective compared to the handheld but the software development costs for the application have to be amortised over the quantity of units sold. That's an issue if this is just a "one off" application. d) The PDA has a battery that needs to be kept in a charged state. I don't envisage this as an issue for the OMRON handheld since it probably extracts power from the PLC serial connector pin allocated for that purpose. e) Although the PDA's OS is in ROM its still a Windows device, i.e. reboots are sometimes necessary, depending on what people do with it! However, I have also had Linux running on a PDA off the SD card - very impressive and extremely stable, but I haven't had the time to write and test a program to operate on the PDA under Linux. Generally your proposal of cable swapping sounds a bit messy if there's going to be lots of occasions where DM memory values need to be tweaked. If you only need this scheme for initial setup then not an issue but otherwise maybe a ultra-light notebook might be better (although I understand that they're not cheap). Anyway, that's my "tuppence worth" ... Eric

[frank.raymond 0]

Eric, Your response was refreshing and well thought out. A handheld or PDA would get me through for the existing task however after a wee bit of thought I realized in the near future I will need to expand on this project. So for the moment I am considering adding an ethernet module along with a pc. A bit costly however the dividends from the future project will more than pay for itself. Again I thank you for your "tuppence worth" frank

[Eric Apperley 0]

No problem. Ethernet is a sensible approach to expansion. The short term cost of buying the ethernet modules will no doubt be recovered by the savings in software development and ease of maintenance due to the standard architecture. Good luck with the project. Eric