PLCMentor.com
MrPLC Member-
Content count
376 -
Joined
-
Last visited
Posts posted by PLCMentor.com
-
-
What they need (and probably dont realize) is a SCADA system. It will do everything an HMI will do and handle data capture. The main difference between the HMI and SCADA is really the data logging and presentation portion of the package. That will allow them to log data, view the system as well as control the individual stations. If you stay with Rockwell then that would be their Factory Talk SE version (not the ME). I would suggest that you look into Inductive Automation's Ignition product. Also I would talk them into logging their data to a database not Excel. The SCADA system will help with visualization of the data, ie trends and charts.
-
Glad it worked! Serial ports in the days of no more serial ports can be fun.
-
Sounds like it just dropped the program due to the backup battery being dead. You can try dumping a program to it. The fault light should go away once it has a program. If you want to keep the program during power down then you will need to get a new battery. Not really necessary for testing purposes.
1 person likes this -
It would take much more than that to get me upset. Now if there was a political thread here...
It really doesn't sound to me as if you get the whole PLC/ladder mentality. You don't need to call a subroutine to activate a device. You put it one place in your program and have multiple conditions that cause the device to be active. There is no need to have conditional JSR's throughout your program. As far as capabilities go, turning on and off a device or activating a piston is exactly the type of activity they are designed for. You do have to understand the mentality of ladder logic.
1 person likes this -
You can do a simple search through your program to find an instruction type. next to the find text box there is a button. Pressing that will allow you to select language elements as your search type. Select the element you want to search for and click on find next or find all.
2 people like this -
Not to mention that the #1 rule with JMP and LBL is don't use them. Well - very rarely. Like most high level languages that have goto statements.k
Now as to examples. You didn't even ask for alternative ways to do what you are trying. You asked about why what you were doing didn't work. To do what you want a simple rung with a timer instruction would work by using the TT bit from the timer to activate your plunger. PLC programs are not really designed to hang around on one task. They are designed to look at a lot of things simultaneously and handle them all at once. To lock out the rest of the program while you operate a plunger is not very useful in the long run.
-
Yeah but it actually has to be a product that my clients use. At this point few of them use Siemens.
-
We all dream about that software package that supports them all, but it just doesn't exist.
1 person likes this -
Actually I don't think its a fair comparison. Wonderware is a SCADA system and Factory Talk ME is just an HMI. If you want to compare then you should be looking at FT SE. If you are looking at SCADA systems then I would also look at Inductive Automation's Ignition. I think it beats them all. I am not really a fan of the System Platform. Wonderware used to be an easy system to get up to speed on and use. You could literally open the box and just use it. With System platform they over complicated it in my opinion.
2 people like this -
Are you trying to do an conditional JSR, i.e., you have logic to allow the JSR or inhibit it? Rarely is that required and if its not require then don't do it. Most PLC programmers I know in the SLC use JSR's for program organization. Then use the logic in the routine itself to handle any conditions for outputs to be on or not. Keep in mind that if the routine is not scanned then the outputs will be left in their last state. Finally how did you place that latch. If you branched around the return then the routine will return without operating the latch. just put the latch on a rung before the return. Also you really don't need the return.
-
Well first if it's a safety issue then the machine should be shut off. I understand that this is a class but generally I do not like software (that can be changed by anyone with access) dictating the safety of my operator.
That said, here is my 2 cents. First you really are not worried about keeping your inputs in a certain state but I can see where your outputs might be important. You will have a sequence for the palletizer. All your pause button will do is stop that sequence from moving to the next step. In a little more detail, your palletizer will have several sequenced steps that will each operate outputs. After some expected action, it will move on to the next sequence step. Your pause logic will just keep it from moving on to the next step. You don't need a temporary end statement.
-
I have seen people go overboard with managed switches but I generally have one on each significant system I install. The biggest networking problems I have ever had seem to be with drive systems. They usually handle a lesser number of packets so swamping the network takes them out first. Your system is pretty small, but the cost of a managed switch is pretty small compared to the cost of the freaky problems that can occur without one. When you have a problem with a network it can be very time consuming (ie, downtime). Time is always expensive.
-
Ok so I might be biased but I don't like the canned 4-5 day courses. They work well for some I guess but more often than not they try to cram a lot in and you remember about half. Many of the college courses are taught by professors that learned out of a book. That is getting better and many community colleges have pretty good programs. We started the PLCMentor.com website because our clients had a hard time finding quality training that met their techs schedules. Taking the tech out of the plant for a week has problems all of its own. We offer self paced training with a few very important extras:
1. We have self paced training and video libraries but the focus is on learning to program. Not hand holding but scratch your head and work your way through it programming. We will nudge but not lead you step by step through it.
2. We offer the ability to send in your class programs and have them reviewed by experienced professionals. Not just does it work, but would I want one of my engineers to install it at a client site?
3. We offer a weekly question and answer session where just about anything controls oriented can be discussed. I have had people bring their programs to discuss problems they are having and to get help with difficult logic. I have had new programmers just trying to figure out the basics. The only rule is that the instructor has to be competent enough in the subject to discuss it. The classes are recorded and we have around 100 hours of past classes on many different subjects. Sometimes its nice just to see there are people out there that know less than you!
The only drawback I ever see is that the student has to be self motivated. Nobody is going to be watching to see if you participate or even try.
Oh and I forgot your additional question. RSlogix500 is used to program SLC500 and micrologix PLCs. RSLogix5000 is for the ControlLogix and CompactLogix platforms.
-
I made a vid on this a while back. It's usually in our paid content, but I moved it to the sample videos for you. Hope it helps:
Or you can just go to the site and follow menu: PLC training videos/RSLogix 500 instruction set
You will have to register on the site to login but the BSR/BSL video will be in the sample video listing.
1 person likes this -
Well you hit upon another of my dislikes - Labview. But that's more of a personal preference. I suspect you will still need some sort of OPC server to talk with softlogix also even with them both on the same PC. This is just conjecture, but softlogix attempts to look like PLC hardware and uses standard methods of communication, ie some sort of OPC server.
-
Well I cant really help but I had to say I like your screen! You may need to give more info about how your tag server is handled and how you handled redundancy.
-
In most instances I would just say no. There are some PC hardware setups that are fairly similar to the robustness of a PLC; however, when you compare costs I suspect the PLC will be cheaper. The windows operating system does not really have the reputation for solid 24/7 operation unless maybe you go to one of their server packages. Also ladder is not chosen because of its mission critical capabilities but due to its (supposed) familiarity for maintenance personnel. I would ask yourself this. Will it matter if I have to reboot my control system periodically? If not then PC control may work for you. I dont have any installations where this would be acceptable.
-
Ahgggk! You are correct! I dont know where my brain was with seeing C5:1 going to 0. It will increment up and down with C5:0.
-
This has to be a school project. Nobody in industry would really want a system to operate like this and nobody would call it a GO switch.
There are several things wrong before we even get started.
1. It looks like the author assumed a reset would set the accumulator to 1 instead of 0.
2. Have to assume the stop PB is a normally closed contact and the go PB is a normally open - pretty normal but should be spelled out. Also I am assuming this is an AB processor due to the counter addresses.
3. Assuming that the counter did reset to 1 then the program will still not work as required. The first press should increment counter c5:0 and set the done bit which will in turn activate the counter down logic in the last rung. This will change the accumulator value of both counters interestingly making C5:1 a 0. The next press of the Go will not cause the motor to stop as the accumulator will be a -1 at that point. Decrementing the accumulator for C5:0 will cause the done bit to reset.
4. Even if C5:1 could get a done bit from this logic, the next rung would reset it when it went to done. Thus the motor rung on the first rung would never see that done bit.
5. The plus is that the stop pushbutton would stop the motor and the go button would start it.
2 people like this -
There is another thing to take into account with this also. Are the existing controllers on four separate independent machines? If so then I would leave them on separate processors. If they are controlling different parts of a combined line or machine then combining them makes sense. The question you want to ask is, "Could I take this down and not affect the others?" If so then keep it on a separate processor. Maintenance, upgrades, etc will be made easier. If taking down one processor requires all the others to be out of service anyway then combining makes sense.
-
I would also ask if there is a reason they have to mask it. Are the other bits used for other purposes? If not a simple move should work and be easier on the next guy. More obvious anyway.
-
I guess anything is possible, but I highly doubt your AB PLC was programmed with Siemens software. Your Logo software was probably used on a LOGO PLC in your plant. Your initial idea of grabbing the program with RSLogix500 was correct. The two manufacturers are very particular about that.
Keep in mind that any program you pull off of a ML1400 is going to come without descriptions or other documentation. All of that information is stored in the RSLogix500 project and is not loaded to the PLC. You will grab the program just not anything that describes I/O, registers, or other comments. What you get will work as a backup, but it will be extremely hard to look at and understand.
-
I see that nobody has commented on this so I will shoot. First I have not experienced this with the 5000 series controllers. I did experience this on one of my first projects that involved a PLC5 rack with lots of analog I/O. The PLC5 supplied its analog outputs via the rack power supply and I had too many cards in the rack for the power supply specified. Not a pleasant moment! Second I am curious about the "standard" 250 ohm resistor. I assume from the text that the resistor is in series with the device. All of the transmitters and other loop powered devices that I have used have sufficient load built into the device to not require an external resistor. Of course having too much resistance on the loop will cause problems as will adding to many devices on to the loop (ie, adding too much resistance). I do agree that the resistor is not necessary with modern output modules or (I will add) field devices.
-
I am not a fan of overly fancy pics on control screens. Many times the important information gets lost in the beautiful picture. In addition imported images if too large can slow down some systems. Simple is usually best but also making sure the information is conveyed in an easy to understand fashion is also important. Since a lot of our development is around process control, we use the P&ID diagram as our "template." Not an imported template but as a go by for our screen development. The screens are developed using whatever built in graphical capabilities the software we are using provides. Now days the available graphics are similar - especially since many HMI/SCADA systems include Symbol Factory. I actually feel that some of Symbol Factory's valves and pumps are too busy and are counter productive to the information I am trying to convey. I generally create a simpler object that shows the information I am trying to convey (run status, fault status, etc). I agree that boxes are not the best looking interface design, but just be careful that you do not make things harder on the operators. Here is a youtube vid that I created a while back for our batching system; however, you can see some of the principles that I mention i the video also.
1 person likes this
SLC 5/04 Output Issues
in Allen Bradley / Rockwell Automation
Posted
The fact that your outputs work with push buttons at the end of your program points even more to the issue that Michael referred to - multiple outputs with same address. It does still sound as if your original outputs were being overwritten somewhere before the end of your program. Why dont you do a quick cross reference of the addresses and see what comes up?