7-segment display

ceilingwalker

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ceilingwalker
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Mar 2010
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Phoenix, AZ
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Good day all. This is not an important project or anything, it's just a guy "playing and learning". Would anyone have a sample program they would be willing to share with me that shows how to use a SLC 500 (5/03) timer to drive a 7-segment display? Thanks much.
 
Do you mean driving each of the segments individually using outputs or perhaps triggering data lines of a BCD driven display? Do you have a specific 7 segment display in mind?
 
What I have are some 7-segment chips (I think is what they would be called) and I wanted to see how I could make them display the value of say a timers' accumulator, for example (or a counter).
 
I am trying to rebuild an obsolete display myself...
You have to take the BCD output into a driver, the driver drives the 7 segment LED display.

Except... It appears there are some very rare IC's from texas instruments that had the converter built onto them. Thus needing just the power and the 4 BCD inputs. The ones I have found spec sheets on are TIL308 , TIL309 and TIL311..

I have also found some old red lion " slave displays " that allow the BCD output to be run right into to display, but they are bulky for my panel mount needs.
 
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this was how i did it, two different versions, depends on the amount of outputs you have available, excuse the airbrushing, company logo and name was there

hope this helps

page1.jpg page2.jpg
 
Ok, just reread the original post, asking for code :eek:. Its close to beer time for me, my mind definetly wasnt at work, but hopefully the hardware side will help
 
ceilingwalker said:
Good day all. This is not an important project or anything, it's just a guy "playing and learning". Would anyone have a sample program they would be willing to share with me that shows how to use a SLC 500 (5/03) timer to drive a 7-segment display? Thanks much.
Click to expand...
There's really not much to this.
Make a chart of the numbers, 0-9, and determine which segments light in each of the ten conditions (0-9).
The just write seven rungs, with as many parallel branches as needed for the numbers that light that particular segment.
Now, once you write it long ways, you may see a method to make the program smaller...
 
If you are using seven-segment displays without BCD decoders, then this can be done in an SLC (indeed almost any A-B PLC), with just two instructions per digit.

Take a look at the SQO instruction
 
With BCD decoders, just one instruction for each 4 digits (max value 9999)

Take a look at the TOD instruction
 
jdbrandt said:
There's really not much to this.
Make a chart of the numbers, 0-9, and determine which segments light in each of the ten conditions (0-9).
The just write seven rungs, with as many parallel branches as needed for the numbers that light that particular segment.
Now, once you write it long ways, you may see a method to make the program smaller...
Click to expand...

It will use many less instructions, and no branches are needed to turn off the segments you don't need for each of the numbers 0-9 ....
 
you can drive 7seg using plc outputs but you need to use current limiting resistors. for 24V outputs, 1.5k or 2.2k will be fine (1/2W). Just make sure to choose right type of display. For PNP ouputs, you will want common cathode display. code can be simple, something like this:

7seg.jpg
 
Last edited:
panic mode said:
you can drive 7seg using plc outputs but you need to use current limiting resistors. for 24V outputs, 1.5k or 2.2k will be fine (1/2W). Just make sure to choose right type of display. For PNP ouputs, you will want common cathode display. code can be simple, something like this:
Click to expand...



Thank you much, all of you, for your help.
 

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