DanW

>They do have some nice capacitive point level measurement sensors. I think I'll email them I assumed you were looking for a continuous interface measurement, so I didn't chime in, but if you're looking for point level devices that can be incredibly sensitive to differences in aqueous composition, I can vouch for Siemens CLS 100 capacitive sensor. The situation was to determine when the resin beads in an industrial grade water softener dropped below a certain point. A bench top test amazed me. A large glass beaker was filled 1/3 with resin beads and then filled with water. I was extremely skeptical that any sensor could differentiate between water and water between resin beads. The CLS had no problem. We installed them and they worked flawlessly for the several years that company was still in business. It's an easy test to perform on a bench test water and iron sludge in whatever dilution is applicable. Dan

If I've understood you, it appears that there are at least two problems: 1) displayed values appear where displayed values should not appear, at random locations on the screen. 2) The displayed values are probably byte swapped, since they are way out range, like ±xx.xxx^17, typical of byte swapped values. Both problems are related to the configuration/programming of Citect, since the Citect 'program' is responsible for - which values Citect reads from the Honeywell controller - what happens with the values it reads (logs to history file, display, use for alarm, etc) - where and when it displays received values The byte swap issue is typically resolved by the Modbbus master, in which it is established which format is used. Although the Honeywell can remap its Modbus values in slave mode, I'm not sure whether the byte format can be changed from the default floating point byte format. I'll see if I can confirm that or not. I scan read some of the notes attached above, it appears that there's some clarification on how Citect handles (changes) floating point byte formats. Dan

The HC-900 is known to work well in Modbus TCP slave mode with multiple Modbus TCP masters, so if each PC is its own Modbus master, then the HC-900 should function well in that mode. If citect runs server based with web HMI's or thin clients with a single Modbus TCP master, then HC-900 would handle that OK, as well. The HC-900 has a default Modbus map, or the HC900 Modbus map can be custom configured to move specific parameters to contiguous Modbus register locations for multiple parameters read requests from a master. If the HC-900 data is showing up OK on one of the PC HMI's then, it it seems to me that the problem on the other PC HMI must be a Citect configuration issue. I'm not sure why a byte swap issue would create the described symptom of displaying values at random locations. But I can understand that the display might flash the wrong values due to the byte swap problem because byte swap always produces extremely large values, like, ±xx.xxx^17 or some such silly number; and I've seen other HMI's flash the value when provided with out-of-range values. Where the values get placed on the screen is a Citect configuration issue, unrelated to the HC-900. Dan

1) Is this a Honeywell HC900 hybrid controller? If not, what brand HC900 is it? assuming it is a Honeywell: 2) Is this problem appearing on a Honeywell brand Operator interface? If so, do random numbers appear or disappear on the Honeywell O/I? If so, please describe which screen, like 4 controller faceplates, or digital in/out status matrix this occurs on. 3) How long does the problem persist? 1 minute during start-up? 15 minutes after start-up? All day long? 4) What do you mean by "starting runtime" Isn't the controller always in runtime mode? What are you doing to get into 'runtime' mode? 5) a) What software (name, version, revision) are you running when you look at an overview with a PC? b) Is this software communicating via the ethernet port on the HC900 controller? c) describe what screen the software is displaying when 'random numbers pop up and disappear all over the screen' 6) How does the 'other PC in the room' prevent you from changing configuration parameters? Have you made some configuration changes that started this random number display action? 7) How would you 'change configuration parameters', if the other PC were not somehow preventing you from doing so? What software would you use, which PC, the one with the random numbers or the other one? 8) How many PCs are involved with this setup? The purpose of each, with respect to the HC900 is . .? Dan

Assuming you mean RS-485 as a multidrop physical layer: What won't work is when the serial parameters, word size (7 or 8 bit), baud rate, or parity, are different for different devices on a multipdrop RS-485 line. For instance, mixing Modbus ASCII with its 7 bit data word and Modbus RTU with its 8 bit data word will cause comm errors. The Modbus RTU spec calls for two stop bits for no parity, but many implementations ignore that and offer only a single stop bit. (Nowadays more slave implementations offer a choice of one or two stop bits). But having a device with 2 stop bits on the same drop as devices running 1 stop bit will cause problems. I'm not familiar with BSAP, one poster inferred that it was a derivative of Modbus, another that it can't co-exist on the same layer. I don't know. The alternative is to use multiple serial ports, one for each protocol. The drawing below shows a multiple port adapter with Honeywell FlameSafeguard running Modbus ASCII on one port, Honeywell Modbus RTU devices on a 2nd port, and former L&N devices running whatever protocol they had on a 3rd port. I can't recall enough details of the L&N devices to remember why they were segregated onto their own multi-drop line. Dan

I've been wracking my brain about how to sense the presence of water without using conductivity. I recall running into a refractive index point level switch once. It was designed to mount into the side of tank. When the liquid level covers the sensor, there was a distortion of the source light beam by refraction, and through some means the sensor detected that and switched states. I'll poke around and see if I can locate that device to see what sort of installation options it might hvae, other than threaded-hole-insert. Dan

Yes, unless the floor is dirty enough to add something conductive to the water. I suspect that it wouldn't work in "Bunny suit" clean rooms..

Waterbug made by Winland Electronics. Plastic housing looks cheap, (was an issue with one Pharma customer), but works OK by sensing conductivity of water on the that contacts its bottom mounted sense strips. Dry contact output. Winland Electronics, Inc. 1950 Excel Drive Mankato, MN, 56001, U.S.A. Phone: (507) 625-7231 Fax: (507) 387-2488 www.winland.com

Phoenix Contact ClipLine product: Order No.: 2832519 Type FL RA SF8 Catalog page information Page 285 (NTK-2008)

A serious drawback to most top-mounted ultrasonic level sensing is that the ultrasonic beam bounces off the foam so the signal indicates the foam or part-way through the foam level, not the liquid level beneath the foam, which is what most people want to measure. Top mounted Radar level faces much the same difficulty. Part of the problem is in classifying the foam. Some foam is very dense, other foam is very 'light', almost like the bubbles kids blow with soapy water and a wand with circular ring. I'd suggest asking a level distributor who handles level if you can try an ultrasonic unit and see if the signal bounces off the foam and gives you what you want. Milltronics (now Siemens) used a mechanical float to get the liquid level and the ultrasonic to get the foam level for a mining application where the foam was really dense, always present and the ultrasonic signal always bounced off the top. With both signals, the DAQ system could dislay liquid level, foam level and foam height. Dan

For the life of me, I can't figure out how what it's purpose is, or specifically how to do anything beyond register. It is totally obscure to me how an actual communciation would transpire. Yes, I can enter someone's email address and invite them to join. Big deal. What's it offer? I've registered, received invites, accepted the invitations, but can't figure out how to proceed or do anything with an invitation. So what? I've found people I already know who are listed with Linkedwhatever and whom I would like to contact, but attempting to contact them involves upgrading for a fee. So what's the purpose? If I already have someone's email, why would I register and use this service? If I don't already have someone's email address, and have to upgrade to paid service, I suspect that I dont't really get their email address, rather that the contact gets some form of obscure note, like an 'invitation' (?) to correspond. How would I know that it even transpired? But how would that proceed? What is the fee for upgrading to actually communicate with someone? Is the fee one time or monthly? or per message? Help me out here. I'm willing to listen, but I don't see the point. Dan

I'm aware of sensing difficulties for rotary kilns/driers, but what are some of the difficulties, for instance in gold extraction? ( I thought current technique was leaching gold from its ore using some toxic chemical )

I realized I made the assumption that 'recipes' means setpoint profiles, with maybe the associated 'event' or two (DO's whose state coincide with specific segments of setpoint profile program). If the recipes involve more than the above, like, belt speed changes or more complicated start logic or whatnot, there can be trade-offs with a 1/4 DIN single looper. I noticed that the West box has a couple dry contact DI's on it, but I did not pay close attention to the specific functionality associated with them. In general, 1/4 DIN loop controllers have very limited, specific functionality associated with discrete input logic, so the thought behind the Micrologix might have been for more sophisticated logic at some point. The point might be to find out what the Micrologix stuff was supposed to do that the single looper doesn't, and it could be to just hold more SP profiles. Dan

It sounds like you have an existing single loop PID controller and that maybe someone else already bought the micrologix stuff? Here's my take on it: I've done temp controls on ovens, furnaces and kilns for 20+ years, and until recently found that most useable stuff for operators (who are not always very bright lights) when multiple recipes of setpoint profiles were involved was a low cost Windows HMI, like SpecView, that would download recipes or on-line setpoint changes into single loop controller over Modbus. Trying to keep track of SP profiles on the controller itself was a nightmare, because of the poor operator interface on the controller. The Windows HMI was needed primarily for the ease of entering SP profiles and maintaining the library of profiles. The same level of complexity for handling SP profiles in a PLC/HMI exists as it does with a PID controller. However, just last week I saw West Instrument Solutions (division of Danaher) new Provu 1/4 DIN single loop controller with an LCD display. It is truly incredible the ease with which this controller/setpoint programmer is configured AND operated. The era of grotesque 7 segment display characters attempting to convey meaning as English alphabet characters is gone. Entire words and phrases appear in fairly well lit LCD display. That makes it operator friendly. The setpoint profile option stores up to 256 segments, but a USB port can load as many config setups as your heart desires. I never thought I'd live long enough to see a functional USB port on a 1/4 DIN controller ! ! ! I will be using these for temp controllers with the setpoint profiler option lots in the future. They even have 1 Mb of memory for tracking PV, SP, or output, which displays on the LCD display as a trend! Like a built-in recorder. So, you ask, how does this play into your situation? Well, if someone has already dished out the dough and bought all the PLC stuff, if I were you, I'd take the opportunity, as an intern, to learn the ins and outs of programming the PLC. It's already bought and paid for. Great learning opportunity. PLCs are a fixture in industrial control and aren't going away. Doing PID puts you several levels ahead of the straight sequence guys. It isn't clear what the business cost of having the oven out of commission is. If the boss is willing to let you spend the next number of weeks dinking around learning PLCs fine. I'd say do it. But if he wants his oven back on line, then the easiest, cleanest, quickest route I could see would be to spend $800 on the West Provu, stick it in the panel hole where the other PID controller is, wire it up in an hour, configure it in an hour, and be running the oven that afternoon. While the oven's running its first profile, you can use the Windows software to crank in a bunch more SP profiles and save 'em on a PC so they'll be there when product DEF or GHI or JKL needs to be run. So tackle the PLC if the owner is willing. If he's not, go get the easiest to use controller/programmer ever made and get the oven running. Dan

Thanks for posting your work-around solution

The last couple Modbus specs (2004, 2006) requires the 03 command to cover the address range from 0 to 65535. That's probably been the case for longer than that, but I don't have documentation to claim that one way or another. That means that the Modbus spec calls for the 03 command to cover from address 0 to 65535, which is 400000 to 465535 (decimal) or 40000 to 4FFFF (hex) However, the original Modicon Modbus used a range for the 03 command to read/write Holding Registers in the address range of 40000 to 49999. Note that 49999 decimal is only 15% of the range of 4FFFF (hex). The 49999 has come to be called 5 digit addressing. The 465535 addressing has come to be called 6 digit addressing. 430000 & 430100 are definitely within the Modbus spec range for 03 addresses. The question is, what technique does Citect use to reach those addresses? Given Citect's prominence in the HMI software market, they'd have to be current in their Modbus master implementation. They're not slackers. Have you tried only using the remainder of the address, omitting the leading 4, since the 03 instruction assumes the 4xxxxx range? Dan

Red Lion sponsors a form of support almost unknown to other companies: they routinely browse the PLC and control related internet forums and have a tech support guy answer questions related to Red Lion products. That is superior service in my opinion. Given that many products play on a nearly level playing field when it comes to technical performance (6 of one; half dozen of another) support can and should play a large role in a buying decision. I've even seen the president's name pop up on occasion. That's unheard of for any other manufacturer, that I'm aware of. Dan

Blogs are for people to rant, and they're there to let everyone do his own thing. Recognizing that, it's your blog, you are entitled to do what you want. This comment is isn't meant as a personal attack, but I find that your blogs are just too full of unknown jargon for my tastes. I have no idea what 'bricking' a router is or what "stove piped" products are. For me, it's a show stopper to encounter obscure, undefined terminology in the first sentence or two of any article and I generally move on when that happens. If I can't understand the first sentence or two, what's the sense in forcing a read of the rest? If unknowns pop up right up front, who knows how much slang is used further on? If that's your intent, fine, it's your blog. But if it were mine, I'd use an asterisk and provide a definition for those insider terms that you already recognize as needing quotes because of their very nature. Dan

I recently ran into a similar situation. I'm a process guy, but a client has an HVAC air handler with a proprietary controller that he wants to replace with COTS control. So what's the control tactics? I haven't a clue, HVAC isn't my background. I bought four used HVAC books, to see if I could figure out enough to do tackle the job. The books have arrived in the mail over the past week. Here's a synopsis from a quick overview of each. (I haven't sat down to read any for understanding, yet). 1) Audel's "HVAC Fundamentals" by Brumbaugh. Strictly residential, no commercial. Not applicable. 2) "HVAC Controls: Design and Application" by John Traister Either basics like drawing symbols or components themselves, like thermostats, valves, actuators, etc. Not applicable. 3) "Control Systems for Heating Ventilating and Air Conditioning" 4th ed. by Roger W. Haines. 298 pages Commercial only, no residential. Organized like a text book. Starts with PID. I wouldn't want to learn PID from this brief overview, but at least it shows the book is truly control oriented. Control components take 66 pages, then control systems. Brief descriptions, large number of diagrams of a wide range of control situations. For someone with some controls background, this is where I'll start. 4) HVAC Controls and Systems by Levenhagen and Spethmann, 320 pages More text, fewer diagrams than Haine's book. Lots of comments drawn from experience, that are not typical in text book. Chapters on Air Handling Units, Terminal units, Heaters and Chilled water supply, distribution systems and Supervisory control. I'll start with the Haines book and then the Levenhagen book. Both look to have good stuff on HVAC control. Dan

Phoenix Contact is a German company, with distributors throughout the world. I get the impression that their market for PLCs is OEM, to complement their connector business. Dan

I have a healthy respect for the expertise that goes into a commercial flame safeguard. What's interesting about the diagram below is all the angled arrows on the circled terminal numbers, connectors to opto-isolators on the front end of DI's to the uP (all internal to the flame safeguard controller. The unit does all sorts of self checks for feedback, initial conditions and whatnot. It isn't complicated logic, but reflects lots of man-years in combustion safety and knowing what to write the logic for.

MS Paint for cropping photos, graphics, images & erasing the parts I don't want. For resizing photos I use an very old version of Serif's PhotoPlus because one can re-size by ratio. MS Word has a drawing tool bar with circles/ovals, rectangles, and arrows (view > toolbars > drawing) I do a lot in MS Power Point because it's easier to move stuff exactly where I want it, than it is in MS Word. So I frequently create a graphics layout in MS Power Point and then take a screen shot of the power point slide and insert the jpg screen shot into MS Word. Dan

>"j=e*B*T^4, where B is the Boltzmann constant" I had thought that was accounted for in the electronics of the modern non-contact IR sensor. I thought most commercial IR sensors, the Ircon, Mikron, Land types did that correction internally, using an 'external; linear adjustment for emissivity. Paul, did you make these math corrections to a 4-20mA conditioned output, or to a signal from a raw thermopile? But to get back to the original issue, non-contact IR sensing provides an average of the temperature in the target area. So if the emissivity varies dramatically within the target area, the readings sill, too. Or is this a situation where poduct A has one emissivity, but when switching to product B, the readings shift because product B has a different emissivity? Dan

Channel in wireless can be one of several frequencies within a band Some intrinsically safe barriers have a "channel" for each wire, single or dual channel? Lot of different useages for the same terms.

Thanks for the link to a Chrysler version. Now it's clear why my minivan's transmission failed so early on. Sinusoidal depleneration. Shoulda known. I had only seen the Rockwell turbencablulator version previously. Dan