PLC vs PAC

I've been getting some emails lattely from suppliers about new PAC Programmable Automation Controllers, could anyone explain the main difference between a PLC and a PAC.

It looks like marketing hype to me. PLCs do a lot more than just ladder logic these days. To call a PLC a PLC doesn't really do it justice but we all know what a PLC is and what they can do. PAC is just yet another name for today's more capable PLC.

sboudreau said:

I've been getting some emails lattely from suppliers about new PAC Programmable Automation Controllers, could anyone explain the main difference between a PLC and a PAC.

Click to expand...

It is marketing hype, however the ones calling their system a PAC generally have a CPU that looks and smells more like a PC than a PLC. They have web publishing, lots of RAM, store all variable information on board, and even allow the user to use unused RAM to load other files for archive like CAD files and documentation files.
The one I am most familiar with (GEIP RX3i) has a linux derived engine.
But remember...
"A rose by any other name still has thorns" or something like that.

I figured it was just some kind of marketing strategy, I checked the comparision wikipedia had and it didnt seem like a PAC was different.

Thanks Guys

I can tell you one difference:
All of "my" I&C techs started work in the 70's and 80's - when they think "PLC" they think I:1.0 (PLC)
they do not think "DiverterGate5-6LimitSwitchOpen" (PAC)

Trying to teach them that you need to change the IP address of the laptop on one of the systems (becuase it has a 10.1... address) makes no sense to them. I havent tried to explain a subnet mask yet

Every so often I wonder if we should have gone with SLC500 (ML1400?) controls in our coal yard, and not Controllogix - I think they'd pick up the SLC much quicker.

(I know that this is a horrible comparason, but there is something to be said for building unnecessary complexity into a system) Your results may vary

-John

not exactly

From what I have read the PAC uses PC processors and has more memory and outperforms the PLC in every way.

I imagine some of them even program like a PC.

However, speed isn't everything.

It seems the world is full of PC programmers who don't understand the advantages of the robust hardware of the PLC.

We tried industrial PCs, they fail in vibration and heat where a PLC has no issue at all.

Can't wait to try one. Then I can have 6 platforms and languages in one room.





What is a PAC?
A programmable automation controller (PAC) is a compact logic controller that combines the features and capabilities of a PC-based control system with that of a typical programmable logic controller (PLC).
PLC Feel
- Modular footprint, industrial reliability
- Wide array of I/O modules and system configurations

PC Power
- Large memory and high-speed processing
- High-level data handling and enterprise connectivity
- Extensive communications capability, multiple protocols and field networks
PACs are most often used for more complex machine control, advanced process control, data acquisition, equipment monitoring and motion control.



http://www.automationdirect.com/adc/Overview/Catalog/Programmable_Controllers

PAC Features
CPU with 7 communication ports and LCD display
Serial ports for master/slave or custom device connections
USB local I/O expansion, Ethernet remote I/O
Plenty of discrete and analog I/O modules, display on analog modules
Easy drive integration
Full-featured ProductivitySuite FREE PAC programming software (a $495 value!)
Hardware auto-discovery
All project files (program, tag name database and all the program documentation) in the CPU
Advanced instructions and task management boost program speed and efficiency
Run-time editing and easy data logging on CPU
Tag name database is friendly and flexible, Help File really helps
Easy connection to Access, SQL or ODBC databases
Import tags into C-more database



http://www.automationdirect.com/static/press/video_tutorials_p3000.html


http://www.automationdirect.com/static/press/video_tutorials_plc.html

Johnster said:

I can tell you one difference:
All of "my" I&C techs started work in the 70's and 80's - when they think "PLC" they think I:1.0 (PLC)
they do not think "DiverterGate5-6LimitSwitchOpen" (PAC)

Trying to teach them that you need to change the IP address of the laptop on one of the systems (becuase it has a 10.1... address) makes no sense to them. I havent tried to explain a subnet mask yet

Every so often I wonder if we should have gone with SLC500 (ML1400?) controls in our coal yard, and not Controllogix - I think they'd pick up the SLC much quicker.

(I know that this is a horrible comparason, but there is something to be said for building unnecessary complexity into a system) Your results may vary

-John

Click to expand...

Do I understand correctly that in your opinion contrologix adds complexity? I myslef think the plc 5 / slc system is much more difficult than logix 5000 systems.

Another plus if someone did their job correctly even if you run up on equipment that has no documentation,comments, or sometimes even electrical prints you will be glad to see that logix system with tags that make some sort of sense vs I:1.0 and in the field this happens a lot.

You can't do SFC and structured text in most PLC's but you can in almost all PAC's.

You can't write directly to databases with a PLC but you can with a PAC.

You can't run C on any PLC that I know of but you can on a PAC.

You can't do Deterministic ethernet (close enough)on a PLC but you can on a PAC.

You can't do integrated motion on a PLC but you can with a PAC.

You can't build your own instructions on a PLC but you can on a PAC.

unnecessary complexity

make everything so simple that it impedes function, then back up a little bit.

most ladder logic can be simplified, just imagine involving PC and PC style hardware and software.

I can't wait to use C# in a PLC, and troubleshooting all those words will be way more fun than even STL.

On small machines a PAC would be overkill and you would likely never use these features but start working with high speed applications and using 8000-1000 IO points and you need many of them IMO.

not exactly

The Plc Kid said:

You can't do SFC and structured text in most PLC's but you can in almost all PAC's.

Click to expand...

Ok , you said most.

The Plc Kid said:

You can't write directly to databases with a PLC but you can with a PAC.

Click to expand...

Ok, but the HMI does if it's running on a PC. Do you need PLC to database connection and you don't have an HMI? You have a point, I am just wondering.

The Plc Kid said:

You can't run C on any PLC that I know of but you can on a PAC.

Click to expand...

CodeSys uses C, makes functions, etc, and its free.

The Plc Kid said:

You can't do Deterministic ethernet (close enough)on a PLC but you can on a PAC.

Click to expand...

What is an example of when you need this on a machine?

The Plc Kid said:

You can't do integrated motion on a PLC but you can with a PAC.

Click to expand...

http://www.plcopen.org/pages/organization/members/voting_members/profiles/siemens.htm

The Plc Kid said:

You can't build your own instructions on a PLC but you can on a PAC.

Click to expand...

Add-ON in RS LOGIX5000
and of course Siemens, Step5 from way back and Step7. In fact FB and FC are the only reason I would use Siemens. DBs are cool too, but limited like a one column spreadsheet.

Everything currently being done in the world of machine control can be done with a PLC, or a PC, and probably a PAC, or embedded electronics.

Pick one based on your preference and design around the limitations or suffer from them.

Or pick the one that satisfies the design and learn to live with it.

Or look out on the plant floor and make a list of all the hardware currently installed, then go search for some other manufacturer of hardware and pick that one. Why do we have 6 different software packages again?

The Plc Kid said:

On small machines a PAC would be overkill and you would likely never use these features but start working with high speed applications and using 8000-1000 IO points and you need many of them IMO.

Click to expand...

speed is needed at times, I have seen PLCs do speed.

A bunch of I/O isn't an issue either, I have seen chemical plants with thousands of I/O running with a AB5 PLC.

Very high speed packaging is probably a different world.

Most things can be done with common hardware and simple software.

Even the complex stuff can usually be simplified to some extent.

I have to no gripe with PACs, I would enjoy playing with one, but picking a PAC just cause, will not always be the best choice.

What's the difference between a PAC and an industrial PC with Beckoff I/O and ethercat?

PC has HMI "Built in". Is even faster and has even more memory.

If more is better, the PC is king. i7 quad core with 16 G ram can do a lot, quick.

PAC is just another terminology in my view. Omron, AB, Siemens generally call their products PLC and they can do anything you want really with all languages available. Marketing hype?
I fail to see why anyone would want to break away from the IEC standard and use C - STL is C like anyway - just another level of confusion for the poor trouble shooter on the shop floor.

PLC is dedicated standalone microcontroller that is hardened against the harsh industrial operational environments. PAC (programmable automation controller) - is like a combination of a PLC with a "PC based" automation system. THe PAC has a smarter brain than the PLC.