Looking for a traffic light control program - SLC 500

[mobobom]

ok, i can see there is a big controversy over the traffic light issue here. Let me start by saying i am not looking for the program i am looking for advice.

I am using the same trainer SLC-500 and the issue i want to discuss is the N7 integer file and F8 float file. I missed a day of class and need to get a general sense of how these things operate on the ladder for RSLogix500.

I have the way I want to write my program in my head, but without the knowledge of N7 and F8 I am at a loss. This was a little impulsive to post so fast on it, i apologize, after i reply i will search the forums.

 

[Steve Bailey]

N7 locations are 16-bit signed integers. They can store values in the range of -32768 to +32767.

F8 locations are 32-bit floating point numbers. They utilize the IEEE standard method of encoding numbers. The range is roughly +/- 10^-38 to +/- 10^38.

 

[RussB]

He has a partial code for a trafiic light. We are using RS Logix and were just wondering/surfing for a program to compare ours to.RCM

Post your code and you will be amazed at all the help you will find here.

 

[darrenj]

EDIT..I dont remeber it being that complicated?? have trafic lights changed??

 

[leitmotif]

Where is this instructor ??

Harry,

Where do I find this instructor. What system (Rockwell Siemens or ?) was she teaching? What level? If she can teach you things then surely I can learn also.

Dan Bentler

I put your message that prompted me below for referance.

Humm...

The questions I asked in response was all serious, they are a joke only in that it only scratch the surface of what a real-life situation engineer would ask. If you had asked for a traffic-light program for a MODEL-RAIL train set, then, the program you "found" might just worked fine. However, it wasn't all clear that was what you had asked for. Coding ladder is easy, engineering a system is not. Also, people skill is essential no matter how good an engineer you might be.

Kc9ih, I too feel that bad teaching is mostly to blame for what we have been seeing. I had one of the best programming teacher last year in a local CC. She used to be a programming manager for one of the company here but life-circumstances had her change her career. she made up power-point and sample programs (incomplete programs) that we have to follow and finish. As the course progresses the work get more challenging and she would give us less of a completed program. It takes someone who LOVES teaching to put so much work into every class, cause no $ can motivate someone like that. Comes to think of it, I should go back, there's so much that I don't know

 

[leitmotif]

The books did NOT say this I think

N7 locations are 16-bit signed integers. They can store values in the range of -32768 to +32767.

F8 locations are 32-bit floating point numbers. They utilize the IEEE standard method of encoding numbers. The range is roughly +/- 10^-38 to +/- 10^38.

Steve where do I find this type of information (with referance toRockwell)? This is the first time I have seen file designators ie N7 with a description of what goes in em - other than timer counter bit (B3) files etc.
I have been wondering why does Rockwell put sequencer info in R6 (was it? am doing at home so don't have all info in front of me) and PID in N10.

Dan Bentler

 

[Steve Bailey]

Dan,

I'm no Rockwell guru. I don't remember where I learned that N files are 16-bit integers and F files are for floating point. To handle floating point, they need to be 32-bit. I know it's a dangerous thing to do, but I assumed that Rockwell uses the IEEE representation since that's pretty much the standard.

 

[Ken Moore]

The attached pdf file is a page from the PLC-5 addressing reference; Publication 5000–6.4.4 August 1995
It gives the details on PLC-5 data types, I would assume that SLC's are the same.

 

[grs]

O: = Output file (O0: actually)
I: = Input file (I1::actually)
S2: = Status file
B3: = Bit file
T4: = Timer file (hmmm, I'm noticing a pattern here)
C5: = Counter file
R6: = ContRol file (All other letter were used, except 'n' which is next)
N7: = INteger file ('I' was used for input)
F8: = Floating point file
BT: = Block Transfer file
PD: = PID file
and so on.

At least, that's how I had it explained to me years ago...