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hotwires

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Everything posted by hotwires

  1. Kenwood NX-700 or NX-800 VHF/UHF radio transceivers have integrated RS-232 modems with a max speed of 9600 baud. I know of two water treatment applications using these radios with Unitronics Vision OPLC's communicating via MODBUS, the longest distance is 10 statute miles (about 15 kilometers). If you're in a non line of sight, long distance situation these radios can transmit as much as 50W/35W RF power and get the job done. If you have line of sight then the wireless ethernet or RS-232/RS-485 bridges would work at a lower cost. PLEASE REMEMBER TO TAKE THE FRESNEL ZONE INTO ACCOUNT in your path study if you are considering 900 MHz or above. Short of having 100' of tower elevation for yagi or parabolic antennas at each end of the link, I have some doubts. The Kenwood radios do require an FCC radio frequency license. Real world application has proven to me they work excellent for low speed, long distance data communication. No monthly fees as would apply with cellular. Probably less RF interference as can be seen in unlicensed 900, 2400, and 5800 MHz bands. Cellular is subject to outages, if not on the same cell tower a fiber optic cable cut could leave you down. The WiFi band stuff...can be an RF jungle out there. Police, fire, and EMS use VHF/UHF land mobile radio for their primary communication for a reason. How mission critical is your control link? The constant (and worst) enemy of all things RF is ice on the antennas. I've seen UHF yagis in power company SCADA use fiberglass radomes over the elements.
  2. It's happened to me more than once in the early developmental stage of programming. Make a subroutine and then forget to call it from the main routine. I've tried to force the habit of calling the subroutine first then builinding it
  3. canyouseeme.org or the likes on a PC inside the same LAN as PLC can confirm if the port is indeed open on the WAN side. Maybe a typo by IT staff, I can imply that because I'm IT tech myself..... it happens sometimes.
  4. +1 Aus, 250 ohm resistor in series probably won't make any difference . I would definitely confirm the jumper placement .
  5. with PLC powered off, put ohm meter between AI and ground (0V). you should see around 37 ohms. quick way to ID a potential hardware issue.
  6. Are JP1&2 jumpers in A position? Default has them as DI's. It would help to take screenshots while in online mode. I assume the zero and 1024 values are direct read from MI14 and MI17?
  7. Wireshark should work as a packet sniffer in this experiment. Should be doable with Enhanced Vision controllers. sorry I can't exactly tell you how to either.
  8. To the best of my knowledge (done a lot with V430's and ethernet), there is NO provision/capability for the Vision line to act as a VNC server. The Unistream line DOES support VNC. i believe creators and gurus here would all advise looking into a Unistream controller for an application requiring VNC access. The remote operator app does work well on iphone in all of my applications. It uses TCP port, I suspect a custom protocol though. not VNC like in it's nature, it uses image caching.
  9. hotwires

    Add commas to numeric displays

    Commas do aid in quicker recognition of thousands place and above. I've noticed having to stare harder and longer when numbers get into the hundred millions range.
  10. hotwires

    User Interface

    Ordered my copy this evening.
  11. hotwires

    Improvements required

    I've got my head halfway around this. Guess you'd have to draw me a picture (joke). barrier is still in terminology. i have a fair grasp of hardware and the architecture of data processing. programming launguages not so much, to many dialects/flavors out there. Pyrhon and PBASIC are only ones I ever actually wrote anything in (and it was nothing vast). I recall Dan Logee explaining the UDFB (local, Function In, and Function out) tags were processed in RAM and never occupied EEPROM (non volitile) memory until outside of the UDFB's process. Is this in anyway analoguos to "passing" by reference versus value? To me passing rapid change in velocity to overtake another automobile on the roadway. or please pass the carrots, or passing a kidney stone. The English langauge is riddled with abiguity
  12. hotwires

    Silly coincidences make me jump!

    Aus, Inevitably some piece of equipment will fail in the same area you were working about an hour after you leave. Then your phone rings, then you explain how you didn't touch it and that it is in no way connected to what you serviced or installed, and then you hear: "but it was working until you showed up". Then you decide if you should: go into hiding, go back and troubleshoot something you shouldn't be messing with, or wait for other folks to show up and confirm that it had nothing to do with you. Fun times. Happens at least once a year to me. I would not advise slashing your wrists. Usually finds resolve within 24 hours
  13. hotwires

    Analog scaling/PID setpoint

    You can enter your own scaling ranges direct in the AI setup section. This is addressed in past forum posts and was also discussed at a training seminar I attended last year. Joe is correct, this forum is primarily composed of fellow programmers (from novices to experts) who have day jobs. Usually within 48 hours you will have a reply. If it is urgent and a weekday I highly recommend calling Unitronics technical support. They will do their best to give you an answer on the spot or within 24 hours if it's a complex or unprecedented issue.
  14. @Ausman i stacked HMI numeric displays od MODBUS RTU STRUCT INT: sessions, success, fail for each of the four RTU's. Incrementation was not sequential in regards to order of slave ID's
  15. Unistream's periodic mode internal sequencing logic (no idea what it is) may have something to do with erradic operations when adding a second slave. I have a program that polls four RTU (RS-232 over RF) slaves and polling order is RTU 1,3,2,4 not 1,2,3,4. Thought this was odd. I poll once every 45 seconds. The RF modems add up to 500mS latency. Offsite pump control doesn't demand high speed updates.
  16. hotwires

    Thoughts on Linux

    Win 7 and up you can create a system image on an external HDD. Drop computer in pool? System image restore. XP had no simple complete OS backup.
  17. hotwires

    Silly coincidences make me jump!

    @Cara Bereck Levy "fusible link" is the term used in the US automotive industry for a length of wire intended to act as a fuse. Happy New Year Ms. Cara 🎉
  18. @Joe Tauser I didn't forget the architchtural structure of MODBUS. I used terminology like: " request packet / response packet" and "exchanged". No data communication is instantaneous (maybe quantum computer would be closest thing I can imagine). I also remember JT qoute: "empirical data is the best data" and wholly agree. My time calculation figured in the send and reply packets (approximations) but NOT: UART, CPU, or ladder execution times. 17 mS is still a far cry from over 500mS. I don't have an intimate understanding of physical PLC processing architecture, however I assume (dangerous word, I know) that it's fairly parallel to PC's and embedded uC or uP (with external chips) control devices (like DMX lighting control consoles and BASIC stamps). Unitream has two CPU's? correct? Panel and CPU, then RS-232 module has UART with CPU that is on a com bus back to the main brain. If I ever get some spare time I'll try to setup a Unistream RTU master to Vision RTU slave and try to measure min time between successful RHR exchanges.
  19. Just a thought: you could try aperiodic ladder trigger on sensor #1, compare for increment of RTU#1 sessions STRUCT integer, that in turn triggers Aperiodic RTU#2, compare detect session STRUCT advancement, in turn triggers RTU#1 again, LOOP. In THEORY this should alternate MODBUS commands between sensors at the rate each MODBUS slave STRUCT count advances. Would be analogous to the MODBUS "function in progress" bit in vision. The system would tell you when it had completed a MODBUS operation, that being the cue for the next. Never tried this exact scenario. I have used session counters to detect a complete cycle of periodic MODBUS exchanged and toggle heartbeat bits. Assuming: The request packet for the Slave address (1 byte) + Function code (1 byte) + Offset (2 bytes) + Number of Regs (2 bytes) + CRC (2 bytes) = 8 bytes. The response packet length will be: Slave address (1 byte) + Function code (1 byte) + Byte Count (1 byte) + Data (2 bytes) + CRC (2 bytes) = 7 bytes. The number of bits will depend on the serial setup (e.g. parity, data bits etc.). Assuming 1 start bit, 8 data bits, 1 parity bit and 1 stop bit = 11 bits per byte. So total number of bits = 15 bytes * 11bits/byte = 165 bits. Now the bit time must be calculated = 1 / baud rate. Taking 9600 baud as an example, bit rate = 9600 / 1 = 104 micro seconds per bit transmitted Giving a total transaction time of 104 micro seconds * 165 bits= 17.16 milliseconds per MODBUS handshake Now there is some internal overhead in CPU to chew it up and spit it out. What part am I missing that makes less than 1 second polls feasible? One thing I'm not factoring in is the response turn around time in the slaves. That would have to be measured or found in spec sheet.
  20. Isn't the ethernet module just a (physical layer) signal interface board? I was told the other Vision/Samba controllers didn't have enough memory to accommodate more than four sockets. V700 must have a unique CPU.
  21. hotwires

    Silly coincidences make me jump!

    I am particularly jumpy when working in or around high voltage electron tube power amplifiers. Even little sounds startle me. I've had other people clap or make a loud bang while I had my head in an equipment cabinet, NOT FUNNY AT ALL! Amazing how the timing can go when you shoot the juice to equipment and something else goes bang, pop, bing, bang or boom. Heart arrhythmia's can certainly result from such events. Happy New Year Aus!
  22. General.VNC Number Of Connections INT32 on a Unistream 15.6" is linked to an HMI numerical display and the "connection counter" seems to be cumulative instead of real time. Right now it is showing "D#6" and there is absolutely NO WAY there are six active sessions at this instant in time. UniL version 1.19 rev 19. Have noticed this for about a year. This in no way inhibits crucial functionality of the process control, just a nuisance to me. In short the VNC connection counter seems to get STUCK. A reboot will zero it back out. Sometimes it works as expected; ie showing zero, then 1 when I connect VNC and back to zero when I disconnect.
  23. UPDATE: I found that SI104 (socket 1) was not set in my SAMBA program, guess I'm thinking of some of the V430's I had tried setting SI 10x values. I set power up value D#10000 for SI104 (10 sec). I'll see how that works out. bad thing is the socket freeze doesn't happen often (can be weeks or months). For some reason I had the impression that SI101 thru SI110 did that for you: SI 103 TCP/IP Connection Keep Alive (Socket 0) Units of 100 msec Note- When value is ‘0’, the function is disabled Enables the PLC to disconnect if there is no communication from the connected device. When TCP/IP connection is established (SI 145-148 = 6) check data transport (SDW 14 – 21). If no data transport occurred during the defined time – perform ‘Socket Init’. Data Transport counter is SDW 38
  24. At random times sockets 0 and 1, 20255 and 20256, server (slave) on V430 and SM43 are freezing up. Usually not both.... thinking it's more port 20255. I've played with the SI for timeouts. SB168 is set to power up at "1". it will still email, web server (V430) will still work, and usually port 20256 will work to let me connect and remote REBOOT the PLC, then the frozen port comes back to life. Any ideas!? I worked a long time on getting a reliable "EMAIL" logical construct; I believe I got that whipped and have had no issues lately. This STICKY PORT issue has plagued me for sometime. Any suggestions/solutions would be greatly appreciated.
  25. Great, not sure if it will present in a LAN environment or not. All VNC clients are on WAN side. Router is DMZ to PLC (panel) IP. My only theory is when multiple clients connect at the same time (which can happen) and then disconnect in random sequence that (perhaps) PLC not detecting disconnect. Not really sure of the mechanics of a VNC session disconnect on host side. I know at 2am that six clients are not still connected. Mobile devices are mostly iphones, if that helps. Operators spot check panel when they get a text msg alarm. Doubtful anyone is staying on 24/7 via their cell phone. Thanks for looking into it😀
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