SLC 500 vs PLC 5

Hey all, ive been given my first PLC 5 project. I was wondering what the major differences are between the SLC 500 and the PLC 5 line (programming wise that is). Ive done 50 or so SLC 500s already. Anything I need to keep in mind when going from the 500 to the 5? Thanks.

PS, these are really old PLC5/10s. Any limitations I should be aware off?

Thanks in advance

Matt

not a bunch, but enough

Well, the first and foremost difference is that the physical I/O
is numbered in octal. Long story as to 'why', just deal with it.

I/O configuration is more of a manual thing, and there's no
checking to make sure the right modules are in the right slots.

BLOCK transfer instruction are a new realm... there are no pseudo files. ('G' files)
All the module data is available, and must be configured.

Maybe a bit more flexibility with the comm channels than you are
accostomed to, but in a good way. (The 3-pin port can be DH+, RIO scanner or RIO adapter)

2 biggest issues:

analog signals - SLC analogs show up right on the input and output tables (ex: word I:7.0) - the PLC-5 must use Block Transfers to read and write the analog signals to and from the analog modules -

plus PLC-5 systems make use of 2-slot; 1-slot; and half-slot addressing in all chassis -

those are the biggest issues - learn those and most of the rest will fall into place -

sorry short on time -

I noticed that the I/O config was drastically different. Does it matter which rack addressing scheme I use?

from the "it all depends" department ...

Matthias von Zorn said:

Does it matter which rack addressing scheme I use?

Click to expand...

we need more information ... is this:

A. an existing application that you're just going to make some modifications to? ... or

B. a new application which you're setting up from scratch? ...

if the answer is A. then the addressing scheme has already been determined ... the setting (for the local chassis) has been made with DIP switches mounted inside the chassis right behind the processor ... if you're online (or have a current offline file), you can get to the screen shown below which will tell you the existing I/O addressing setting (again, this is only for the local chassis (the one with the processor in it) ... use the Help button to navigate to the handy little "cheat sheet" as shown ... note: when it says "I/O pairs" it means that one of the two slots in the pair must be reserved for an input module ... the other slot in the pair must be reserved for an output module ... specifically, the pair cannot be used for input/input nor for output/output ...

[attachment]

if the answer to the question above is B. then you need to tell us more about the I/O you're going to be using ... specifically, how many chassis and what type and how many modules are to be installed in each one ... Ken Roach is an excellent resource for helping with this type of problem but I'm sure that others around here can help too ...

Differences SLC500/PLC5 off the top of my head:

IO bit adressing scheme: SLC 0-15 (decimal). PLC5 0-7 + 10-17 (octal).

File sizes: SLC max 256 words (0-255). PLC max 1000 words (0-999).

SCP (scale with parameters) instruction: Does not exist on PLC5.

Oneshot instructions: SLC "OSR". PLC "ONS" + "OSR" + "OSF". There are differences with regards to where the oneshots can be placed.

SLC hardware configures itself when you pick and place modules in "IO configuration".
PLC hardware needs to be set up with dipswitches in the chassis.

SLC IO adressing is straightforward as compared with the PLC5 because of the 2-slot, 1-slot, ½-slot adressing scheme. 2-slot utilises the available adress space best. ½-slot is most flexible.

SLC analog IO has fixed and straightforward adressing. PLC5 analog IO needs to be setup in the IO configuration AND needs to be updated with block transfers.

SLC ch 1 node adress and speed is set by software. PLC5 ch1A is set by dipswitches.

I think that an SLC5/04 is actually faster than a "classic" PLC5 processor.

edit: That PLC5/10 does not allow any remote chassis. So you are limited to max 16 IO modules (with an external power supply).

But you would be hard pressed to have more IO with only 6 k program memory to play around with.

Also, there is no EPROM, so check the date on the battery

I think I can answer one question

PS, these are really old PLC5/10s.

Click to expand...

...so there's only one chassis, no option for RIO (unless he uses a sub-scanner).

The 5/10 didn't have very much memory, so be careful what you attempt.

There's a significant difference in memory allocation that you need to bear in mind. If you create non-consecutive program or data files there is a penalty in the PLC5's that you don't get with the SLC500's. Each file has an overhead of 6 words (address pointer). If you create a file number 10 and a file number 100 with no files in between, then on the PLC5 there will be 6 words reserved for each of the non-existent files 11 to 99 - over 500 words which is a significant hit on a 5/10. This doesn't happen on the SLC.

One more thing to remember, that's MCP (Main Control Program). In the SLC, Ladder file 2 is always there, and you jump (JSR) to the others; but with the PLC5 you might have to tell the PLC that it's there - in the Processor Status, look for MCP, tick the ones you want (or add them). (eg file 2, 4, 6, etc)

You don't necessarily have to put JSR U:3, etc like in the SLC (although you can); you could just have 10 MCPs set up. Big advantage is they can quickly be disabled, but disadvantage is you could forget them!

Wow, lots of great information. Thanks alot, this is exactly the kind of advice I was looking for. These are existing machines that need to be reprogrammed to fit into a new installation. 9 different PLC5/10 setups. There will be 3 new slc based machines as well as a wonderware system. Thanks again.

A couple of other things...

The PLC5 supports Sequential Function Charts. I think the 5/10 is a 'classic' plc so you only get one SFC (must be in file 2) and there are no MCPs.
So you can construct a program similar to a SLC program by issuing jumps from file 2.
As was stated before, try to keep your data files together somewhat as 'non-existent' data files between two non-contiguous existent data files will take up memory.
There are a few significant differences, but by and large the look and feel is pretty similar.

Keith

Also, it seems one of the machines has a PLC5/40 in it. Anything besides comms and memory that is different than the 10?

Don't know about /10s but a 5/40 allows you to create program and data files while online in program mode. SLC requires you to be offline and download.

Don't know off the top of my head which PLC's this applies to (but definately 5/15's), but a feature i've found very useful is the "Partial Download" option from RSLogix5. Not available with SLC's but this allows you to create new Data tables and Ladder files without having to re-download an entire program.

Regards

Guy Martin

The 5/40 is a 'new platform' plc. AB went through a PLC5 re-design in the early '90s. The 'new platform' plcs is the result.
The MCP thing that Moebius refered to earlier is available with the 5/40. You can also have multiple SFC's if you like that sort of thing.
The 5/40 will have four comm ports on it that will support either DH+ or Remote I/O. It also has a 25-pin DF1 serial port on the front. The big hole on the front with the door across it is for a memory module.
The compute statement came in with the new platform processors so you will have that with the 5/40. In general the new platform processors have an expanded instruction set compared to the classics.
Having said all that, if you write a program that works in the 5/10 you can port it to the 5/40 and it will work there, too, more or less. You may need to massage SFCs a bit and you will need to set up at least one MCP. The 5/40 gives you everything the 5/10 gives you and more. The only thing you need to keep in mind with the 5/40 is the MCPs if you keep the programs the same. I don't think program file 2 is automatically defined in an MCP. You will probably need to do that manually in the 5/40 or nothing will run.

Hope this helps.
Keith

A useful site to try is

http://www.ab.com/

If you've not been there before you have to register (dead easy), then this takes you to:

http://www.ab.com/index.html

Click on
Publications Library>

then either
The Automation Bookstore
or Manuals On-line

heaps of info to download on the different models


M

btw Keith - you're right about the MCP - none are set up by default