What version of SLC500

[muzikant5]

Hi

Can someone explain to me how the memory size limits the size of your program. For example an SLC5/01 has 1K of memory, how many rungs of program would that limit me to, or does it limit the number of Inputs and Outputs I use. If I want to control 12 outputs and 6 inputs, what kind of memory should I have at least and maybe even some spare memory in case I want to expand my program in the future. What's the minimum memory I should go with, 4k, 16k, 32k...

Also is it better to buy a TRIAC output card with SLC500 since I'll have to control coils which operate at 115VAC, or is it better that I use a DC Output card and have Solid State Relays. What's better in terms of money and life expectancy.

What's would I need when putting a SLC500 together, I'm assuming a Power Supply, CPU, Input, Output card. Correct me if I'm missing something.

And final question is what kind of cable is used to communicate with SLC500, is it Ethernet based, and how complicated is it to set up communication with the computer.


I know some of my questions might sound stupid, but I'm really new to PLCs and I would greatly appreciate all the available help and advice I can get from you guys. Thanks for your help in advance.

[mgvol]

Try the selection guide at the link. Everything you need to know about SLC hardware and capabilities.

http://literature.rockwellautomation...g001_-en-p.pdf

[muzikant5]

Hi mgvol thanks for the link. I would still like an opinion from someone who actually used this PLC in field. For example I know that TRIAC output cards have some leakage current, and since I'm planning on controlling AC coils on directional valves that are 4W, 115VAC so current required to turn on these coils is fairly small. Is it better to use a Solid State relay maybe but even they have leakge currents. I won't to stay away from mechanical relays because they have moving parts and won't last maybe a month.

Also what software do I need to communicate with SLC500.
I'm assuming I need RSLogix 500 and RSlinx. Do I need a 1747-PIC cable also.

THanks for the help.

[plc noob]

This is what we use http://www.ab.com/industrialcontrols...ys/700-hl.html

You will notice that they have a built in shunt for leakage current.

You can get these in solid state relay or mechanical and they still act as interposing relays.

This is the way to go because if a coil shorts,Field wiring damaged,etc the expensive output card is protected all you have to do is fix the field problem and replace a $5.00 relay vs. destroying a card that costs several hundred dollars.

[muzikant5]

Hi


Thanks for the reply. Would a solid state relay used with a dc output card be the same? I mean DC output card would be isolated from the coil with the relay.

[mgvol]

Regarding software & cables:

Yes, you will need RSLogix500 and RSLinx Lite (comes with Logix500). As far as cables go, that depends upon which CPU you go with. The 5/01 and 5/02 CPU's only have 1 comm port - an RJ45 connector that is DH-485 protocol. If your PC has a serial port, you would use the 1747-PIC; if all you have are USB ports, use 1747-UIC with a 1747-C13 cable. The 5/03 CPU also has the RJ-45 port for DH-485, so the cables mentioned above will work. The 5/03 also has a DB-9 serial port, that is default configured for RS-232 DF1 - a 1747-CP3 or any null-modem serial cable will work for this port.

The 5/04 CPU has a DH+ port, as well as the DB-9 port like the 5/03. For the DB-9, see the cable recommendations above; for DH+ you will need either a 1784-PCMK card for your laptop or a 1784-U2DHP USB to DH+ converter cable.

Finally, the 5/05 CPU has ports identical to the 5/03 (RJ-45 and a DB-9), but the RJ-45 port on the 5/05 is ethernet. For the ethernet port, use a CAT 5 crossover cable or a regular CAT 5 patch cable if you are using an ethernet switch or hub. The serial port uses the same cables as the 5/03 and 5/04.

[Mickey]

Originally Posted by mgvol

Regarding software & cables:

Yes, you will need RSLogix500 and RSLinx Lite (comes with Logix500). As far as cables go, that depends upon which CPU you go with. The 5/01 and 5/02 CPU's only have 1 comm port - an RJ45 connector that is DH-485 protocol. If your PC has a serial port, you would use the 1747-PIC; if all you have are USB ports, use 1747-UIC with a 1747-C13 cable. The 5/03 CPU also has the RJ-45 port for DH-485, so the cables mentioned above will work. The 5/03 also has a DB-9 serial port, that is default configured for RS-232 DF1 - a 1747-CP3 or any null-modem serial cable will work for this port.

The 5/04 CPU has a DH+ port, as well as the DB-9 port like the 5/03. For the DB-9, see the cable recommendations above; for DH+ you will need either a 1784-PCMK card for your laptop or a 1784-U2DHP USB to DH+ converter cable.

Finally, the 5/05 CPU has ports identical to the 5/03 (RJ-45 and a DB-9), but the RJ-45 port on the 5/05 is ethernet. For the ethernet port, use a CAT 5 crossover cable or a regular CAT 5 patch cable if you are using an ethernet switch or hub. The serial port uses the same cables as the 5/03 and 5/04.

mgvol,

I'm saving this for future posting ( if you don't mind).
This question comes up a lot.

[muzikant5]

Thanks for the reply guys it really clarified some questions for me. If someone could briefly explain how the PLC memory limits you I would appreciate that very much.

And another question off topic, any suggestions on how to control a Timer Preset value from a potentiometer or some sort of a switch. Would my only option be to go with analog input or I can manage to do it somehow with digital input.

Thanks for the help.

[plc noob]

Well you really can't say with x amount of memory you can do x amount of rungs,xic,xio,ote,etc

Long story short it depends

It depends on how you structure and assemble your program.

An example is unused timers.Even if you have a timer element created in a timer dta file and you don't use it in your logic it still consumes 3 words of memory.

It is possible to run an entire machine in 2 or 3 rungs using sequencers but i would not recommend it.

Best thing is to get some idea of the program size in i/o and complexity before purchasing a processor

[muzikant5]

Ok thanks for the reply plc_noob

Lets say I'll have 4 timers, 3 outputs, 2 inputs (digital)
How much memory would be sufficient for this type of program

[Mickey]

Originally Posted by muzikant5

Ok thanks for the reply plc_noob

Lets say I'll have 4 timers, 3 outputs, 2 inputs (digital)
How much memory would be sufficient for this type of program

See appendix C of SLC500 instruction set manual below.

http://literature.rockwellautomation...m001_-en-p.pdf

[hd_coop]

Originally Posted by muzikant5

Lets say I'll have 4 timers, 3 outputs, 2 inputs (digital)
How much memory would be sufficient for this type of program

I don't believe you could find a PLC which didn't have enough memory for 2 inputs, 3 outputs and 4 timers.

[PLCMentor]

Hopefully you are reading the manual section that Mickey posted. What I dont think you are getting is that each and every instruction and data register created uses a certain amount of memory. Add up your timers, contacts, outputs, etc, then add up the data elements you will need with them and use the table to determine memory use. I can say that most anyone here wouldn't look at the book for the list you gave because there isnt a SLC out there that couldnt handle that. No reason to look it up for that.

To get a Pot value in the PLC you need analog. Discretes are just 1's and 0's. You might be able to have a group of set preset time periods that can be associated with some switches to acheive this without the pot.

Russell

[Ken Moore]

You could use a BCD wheel, hardwired digital inputs. You will need 4 discrete inputs for each digit of the BCD wheel, so a 4 digit number will require 16 inputs. You would be limited to integer values.

Then in the PLC you convert the BCD to binary and move it to a timer preset.


ken

[Ken Moore]

For the small program you are talking about, a "smart" relay would be sufficient.
Can't do any math, but for straight ladder logic they work great for small non-critical applications.
You could change timer presets from the LCD screen.
Something like this: http://www.factorymation.com/s.nl/sc.2/category.22/.f