Upgrade SLC 5/03 to SLC ???

Orn Jonsson

Member
Join Date
Apr 2002
Location
Boise Idaho
Posts
125
Hi Folks,

I have a machine with a SLC 5/03 16K and it is basically out of memory. I still need to add to the ladder logic as I am integrating this machine with two robotic transfer machines.

The dilemma which I have is that I am currently using both ports on the SLC 5/03 and by going to a 5/04 32K CPU I will end up with a DH+ port which I have no real use for and I will loose my DH485 port.

Currently The RS 232 port (port 0) is talking to 3 Delta motion controllers (DF-1) "I think" via RS232-RS485 converter. And the DH 485 port (port 1) is talking to a Automation Direct 'EZ Touch" Touch Screen via 1747-AIC module.

I gan get DH+ card for the touch screen for around $1000,

I can get Ethernet cards for the 3 Delta Motion controllers for about $3000 ( requiring a SLC 5/05)

Or I can sit down for about a week and rewrite the previous dudes program hoping to save at least 1 - 2 K of memory.

Any suggestions

Thanks,

Orn
 
Why not add another SLC500 and setup a small network? What would another SLC5/03 and rack cost, or maybe you could use something even smaller that could work on the DH?
 
Yo, Orn,

Unless there's some reason (proprietary code?) why not post the other dude's program here? There are plenty of guys around who would be willing to take a quick look at it and recommend any obvious memory-saving steps that might be available. Most programmers leave "holes" in their data tables, forget to remove unscanned rungs, etc. There's a remote chance that you might be able to simply "reorganize" the existing code and recover 1K or 2K of wasted memory. RSLogix has several tools that can help you "search and replace" addresses - and even transfer the documentation descriptions for you at the same time. The trick behind doing a project like this successfully is to get organized before you start actually moving things around. Make a chart: "I'll change B3/44 to B3/14", etc. - and then check off the steps as you go.
 
i know this may be a long shot but do they do a processor card with a bigger memory u said u were gonna use a slc 5/03 16k processor, and i think they do a slc 5/03 32k processor card, if this is so then this may the easyest option.
as i think the processor program will just download into it.
i hope this may be of some help?

andy :)
 
SLC ???????????????

I have been advised to show caution when networking multiple PLCs for the same machine. Reason being that you really don't want to depend on the network link for say a permissiv or an interlock.....

I don't know much on Networking multiple PLCs, what you can and can not do, but I guess now is the time to learn (fast)......

Apparently the SLC 5/03 series comes ether 8K or 16K or else I would be a up and running.

I would love to post the code here but don't want to violate any propietary arrangements ......you know...
However, I could easily describe the process and how the the current program (mis)handles it.

Any hardware change will cost me a minimum of $4000, so right now I think I'll start diggin into the old code.

Any further suggestins will as always, be appreciated
 
I dont know why

I have been advised to show caution when networking multiple PLCs for the same machine. Reason being that you really don't want to depend on the network link for say a permissiv or an interlock.....

Its common to use a Master/Slave in many machines for the purpose you have. The Master initiates the start for run part of the slave. I have 18 German built machines that have 2 parts to the way they operate, the second part(slave) is initiated by a command from the primary(master) section.

Think about it, a mechanical switch is used in many cases to provide an input that initiates an action, what is more reliable overall? A mechanical switch or a solid state device like a plc?

Use the tools that are available, if it means using multiple plc's on a network then thats what you do. The technology and use have been around for many years, there is no reason not to use it.

Note: dont depend on the network alone for safety aspects.
 
If you do it right a networked system is very reliable. As mentioned above, you should divide your I/O and logic so that machine specific protection and critical control functions are in hte same CPU that has the hardwired I/O for those functions. Then you use the network to exhange supervisory commands (run faster, setpoints, etc.) from the master to the slave.
 
Suggestion

Orn, as stated above the AB networks are usually very reliable, but not always fast enough to handle error situations. I recommend that you minimize the timeout times in the MSG blocks. In addition the communications should be augmented with a emergency stop system.

This can be done by connecting the 3 RMCs together as follows:

The RMC's CPU outputs are a SSR with a + and - connection.
The RMC's CPU inputs are differential with a + and - connection and can be connected in either sinking or sourcing configurations.

Connect CPU input 0+ of all RMCs to 24 volts and tying the CPU input 0s - together in parallel. Now connect the CPU input 0s - connections to the three CPU output 0s in series where the last CPU output 0- is connected to common. Now when all three of the CPU output 0s are on, current will be drawn through all three inputs which indicates everything is fine. If any of the RMC outputs go off or fail to conduct current then all three of the RMCs CPU input 0s will de-energize. Now each of the RMCs can detect the inputs going off and a emergency stop sequence can be initiated within each the RMCs.

This can happen very quickly in much less time than a PLC scan, or a MSG block update.

Orn, the system that exists now is a network. You should check to see if the previous person has the RMCs wired together as described above. It is also possible to connect the PLC in this emergency stop circuit so the PLC can detect or initiate emergency fault conditions.
 
At 16K you must have a fairly good size program. I agree with some of the other posts look at your code for holes that are eating up memory. I find a good place to start is the data tables. Check each one for usage if you have lots of spares a bit consolation may help to free up memory. If you connect another SLC then keep the message times as short as possible and set up a heart beat bit to check the messaging in both directions.
 

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