Bill Linne

This is toooo sweet! Thanks, Mickey!! When I saw that the example was using DH+ (I was trying to use Ethernet) I connected a CLX processor to my DH+ network and Bingo, worked first time. Coolest PLC trick I've seen in a while. Proves, yet again, the exceptional value of this forum and helping one-another. Regards, Bill

Good Morning Gents: I also tried Mickey's way this morning, but get a "Connection Was Broken" error in the message. I note that he uses multi-hop, and that multihop allows for the "path" to be designated. Is that the trick to that method. I agree it is VERY sweet, and I'm anxious to make it work. (In fact I "tunneled" into my PC from home last night to try it, got the same error, then tried again this morning.) Thanks to both of you for all the help! Bill

Excellent, as always, Ron! I'll give that a try first thing tomorrow. Thank you! Bill

When you say Linx is properly configured, does that include selecting the driver in the "Communications" "Configure Client Applications" "Interchange Port Mapping" dropdown? I don't have Lite installed, but I'm pretty sure Lite uses that functionality. Without it configured, Linx will see only what is on the local machine.

Thanks, Ron. I knew you'd have the answer to that. I now remember the jumper, as I have a couple of the P-7's presently in service. Your explanation also explains (I think) the communication cable between power supplies when two of them live in the same chassis. I'm home now and pooped. Been one of "those days" (a fitting conclusion to one of "those weeks"!). We'll make it a point to post the other details asap. Regards, Bill

Thanks everyone for your input. "Waterboy" and I work together (he is off today). I think the power supply may be the issue. We are expanding the plant, and recently swapped an 8-slot chassis out to a 12-slot (to support installation of another 250 HP pump). All fine up until two days ago when we had a shutdown opportunity and actually populated the chassis with the four new modules. Two of them are analogs, one input and one output. The other two are digital, one in and one out. They have nothing wired to them as yet. Next week I have another shutdown opportunity, and intend to install a 1771-P7 power supply in place of the smaller, slot-occupying 120-volt supply in there now. (Which brings to mind a question: Can the P-7 be installed, connected, and powered-up while the PLC is being powered from its existing power supply? (Essentially operating them in parallel.) I know multiple power supplies can live in one chassis together, so why not one in-chassis and one off-chassis? Then we could pull the in-chassis supply without shutting down. (It is usually possible to get a shutdown each month for a few hours, but this is to satisfy my curiosity, really.) Thanks again for all the ideas. We will certainly advise the outcome. If the P/S does not do the trick, we'll post the logic. It is very basic, and worked fine for years until the situation I described above. Then the BTR's of the existing and new A/O modules both started intermittently erroring. Sometimes Done, sometimes Error. No consistency or pattern. I understand we don't even need that logic, but it should work, nonetheless. Bill

That works pretty sweet, TW. Thanks! Bill

Since installing Logix 5K V16, the Search function will not find much of anything. Even when there is an exact match on the next rung. I've checked everything multiple times. A Google search brings up one thread where one other guy had this exact problem, and the response was to do an ALT+2 before the search. All I get when I do that is a "bonk" sound from the PC speaker! (No matter how hard I hit the keys!!!) Can anyone help? My Tech Support is Mon-Fri 0800-1700, so my next window is not until Wednesday the second of January. I've searched the Knowledgebase to no avail. Gonna waste two perfectly good days of initializing a new project if I can't get this resolved. Thanks for ANY help you can provide. Bill Nevermind! Once I figured out that the Knowledgebase absolutely hates Firefox, I switched to IE and found the answer. Had to do with the configuration of specific areas of each type of possible sub-routine to be searched. Why "ALT+2" worked for one person is still beyond me, and I'll be interested in finding that out. But for now, I'm in business. Bill

Aha! That 'splains it. Thanks.

I can hardly wait for my next opportunity to spring that tidbit on one of our engineers. We are in the midst of a $50M plant expansion, lots of opportunity to deploy such wisdom! Bill

Thanks, Mickey! I found it in a different format, but the answer is the same. Bill

Can the Remote I/O connection on a PLC-5/20-E be used to support more than one Remote I/O Adapter? I have a short-term need to support additional I/O during the Plant Expansion, then an entire chassis gets eliminated. Better Ideas? Thanks, Bill EDIT: I found the first answer. Yes they can be daisy-chained. Not sure if there are "better ideas" . . .

And one thing that MSG reads will not allow you to do is "report by exception", or in other words, send the data only when it changes. I've found MSG Writes to be useful (in spite of their increased 'housekeeping' requirements) when you need to update the distant processor infrequently as the situation changes in the source processor.

Got it! Trial and error (ad nauseum) reveals that right-clicking the first CNB gives an "add module" choice (seems strange to add a module to a module!) but then you configure a remote chassis CNB with which the main chassis CNB is to communicate. THEN you can select the chassis number and what-have-you. Sanity restored!! Bill

I am trying to find the A-B manual that outlines how to properly configure 1756-CNB's. I have a project involving the Logix processor in one chassis, and two additional chassis in the same control cabinet (lots of I/O). None of the hardware is on site for me to play with, and I need to configure the I/O for these additional chassis so I can enter the tag alias info. Cannot find the source document explaining how to work the I/O configuration to add "Rack 2" and "Rack 3". I'm not even sure the vendor has that part correct, in the PLC-5 world the processor would be in rack 0, not rack 1. Any help on locating the documentation would be most appreciated! Bill

Most excellent, Gnex! Somehow the registry keys had /docs/ entered into each of the paths called out in your fix suggestion. Removing those references solved the problem. Thank you! Bill

When trying to install CPR 9 on an XP PC, I get the following Error message: Any ideas? A search of the Registry finds no such key. Thanks, Bill

I'm trying to put a counter in a file (file 4) that is scanned every one second as controlled by an STI. Whether I make the rung unconditional or not, or use a ONS or not, nor anything else I can think of makes the counter increment. I've tried setting a bit true within file 4, then setting it false again in file 2, and several variations of that theme, with and without an ONS instruction in front of the counter. What am I missing? The idea is to verify that file 4 is actually being scanned every second by examining the accumulator of the counter several hours after resetting it. (Just to verify what I suspect is perfectly accurate.)

Thanks a million, Ron! I actually preset the first counter to 32,400 (nine hours) then cascaded another counter. And you're right, I misread the ADD advice, sorry Mickey. Bottom line is that the timing of the STI is dead on, so that is not the problem. The situation is that I'm using the same multiplier to derive engineering units (MGD) in one section of the PLC that controls the speed of the influent pump (I.E. Plant Operator wants 15 MGD, VFD runs pump to produce 15 MGD). In the STI logic, using the same math, I totalize the flow once per second. The TOTALIZED daily flow is significantly less (yesteday should have been 12 MG, totalizer came up with 10.6 MG). Got me scratchin! Thanks again, guys. Bill

That is exactly what I did to start with, Mickey. The .CU bit goes true on the first scan and STAYS that way! I still don't understand that, and I tried several variations on that rung. Ultimately had to reset the .CU bit from a non-STI scanned file to make it work. I'd be very interested in hearing the explanation, believe me.

Found it! Added an unconditional OTU in file 2 to reset the .CU bit of the counter. Works like a champ!

Todd: The plant for which I am responsible is one of those that puts the Cl2 into the water, and I am not a fan of flow pacing so we don't use that technique here. My only experience with sodium thiosulphate is in tablet form, and we use it if we need to "blow-off" (flush) a pipe and water will go into the storm drain. All that is to explain I know little about dosing the stuff . . . so, other than wasting chemical, what is the down-side of too much sodium thiosulphate? If the chemical guys tell you you need xx volume of sodium thiosulphate per unit flow, then I'd say all you need the Cl2 analyzer for is to be sure your metering pump is working properly. I have no example logic for you. If you Google "flow pacing" you'll get several good explanations of the good, the bad, and the ugly. One of the typical down sides of flow pacing is that you must setup for worst-case scenario. In your case, if influent Cl2 is typically .5 ppm, but can reach .75, you'd need to dose sodium thiosulphate adequate to neutralize the higher value. Anyway, I hope that helps a little bit. Let us know what you decide and how it goes, eh? Bill

I'm confused by this part. Seems like you'd slow the pump if the Cl2 goes up (in order to maintain a constant Cl2 value). Or, are you KILLING Cl2 with the product from the pump? What you are contemplating is called Flow Pacing, and it involves controlling pump speed proportionate to water flow (through the new meter). The typical advantage would be faster response. You need not wait for the Cl2 analyzer to take and analyze it's sample and output the result to the pump controller. You just vary pump speed based upon flow through the new meter. Regards, Bill

I would look for N7:0 being used as the control block for some other instruction (like a MSG for example) and therefore N7:5 is periodically being overwritten. If that's the case, writing a "foreign" value to N7:5 could also cause the MSG (or whatever it is) to operate erratically (or fail outright). Do a search for N7:0, N7:1, N7:2, N7:3, N7:4, and of course N7:5. If any N7 address below 5 is being used for something that involves more than one word, you've likely found your problem. Certainly could be another PLC writing data to that register, too. Or, an input module could be configured to write there. SOMETHING is overwriting your data, all you need do is find it. Been there many times, believe me! Good luck, Bill

So far not mentioned is that the parameters of the LIM instruction may be reversed. For example, if you want a rung output to be true after 8pm and until 6am, enter 2000 as the "Low Lim" and 0600 as the "High Lim" and S:21 as the "Test" parameter. With the "Low Lim" a higher value thatn the "High Lim", the output of the instruction is opposite that which you might expect. Bill