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PAC or PLC


VINCHON

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:book:

We have to redesign a system combining image acquisition and positionning

We have to replace a APril PLC

we have to control movement with 4 axes using already existing servo motors

we have normally two choice

either doing the acquisition with NI hardware and LV Software and communicate with OPC With a real PLC

or

doing everything with Labview RT and using a PAC (CRIO, or CFFP or CPXI)

What do you think is the more reliable solution

Best regards

Thibaut

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If you want reliability over a long period of time and guranteed execution time, you should go for the RT solution. I don't know if any of NI's hardware can do image processing (other than the CVS), but if a PLC did it, then I assume it's not too complicated.

I have done systems where a PC is the controller and they do work, but only under certain conditions -

  • Nothing terrible will happen if the system fails (because of anything from problems with the OS to a bad cable).
  • You don't need real-time control.
  • The computer can withstand the environment its in.
  • The system is completely clean (no internet, no games, no anti-virus, etc.)

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PLCs are great. They don't do much, but they are very reliable. Some brands are inexpensive as well. NI hardware is expensive, but it works great.

Although I like to mix PLCs with NI DAQ cards, a local consultant for my company doesn't. He'll specify and use SCXI and $300 PCI serial cards (if necessary). I can't complain because they tend to be fixed bid jobs and he can't afford to fight with hardware incompatibilities. In the end, the solutions work very nicely.

LabVIEW is great. I really enjoy programming with the language. I can't say the same for some PLC programming languages. PLC programming tends to be much more limiting than LabVIEW programming.

The individual pieces don't tend to be the problem, the integration is the bear. Hardware companies in general don't do too good with software. Don't expect wonders from an OPC server from a PLC vendor. I'm not sure about LabVIEW 8.2, but in the past, the standard LabVIEW OPC client is not very good either.

I use a conservative $100/hour for development and testing labor costs. This will probably be your biggest expense. This number gets higher as you add more components, especially from different vendors.

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Salut Thibaut Ca va?

I would go for a NI- HW Solution. Usually the HW cost is much more than a PLC solution. But it's usually much easyer (and faster) to programm...

So the final cost will be probably lower with a NI solution (exept you plan to make a few hunderts)

I have done (or still doing) a wind- tunnel control system using NI HW & SW (PXI) including NI Motion Controller (PXI-7358 8-Axes) for third party Drives (servo Motors) and hydraulic zylinders- and this works great. (and eaven makes fun)

http://forums.lavag.org/index.php?showtopi...amp;#entry20308

I am also controlling a MAXON DC Motor with a MAXON Drive (Epos) over RS232 with LabVIEW for a Inclinometer test bench and this works also fine.

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Hi Martin

Your Project of wind- tunnel control system seems very impressive.

I have several questions bout your system

Q1) did you had to use Labview RT and Labview FPGA for your control system

Q2) which kind of motor are tou driving (do you need a big force couple, what is the weight of the system?

Q3) do you have some emergency stops constraints

Q4) Why did you choosed PXI and bot compact RIO our Compact Field Point?

Regards

Thibaut

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Q1) did you had to use Labview RT and Labview FPGA for your control system

Q2) which kind of motor are tou driving (do you need a big force couple, what is the weight of the system?

Q3) do you have some emergency stops constraints

Q4) Why did you choosed PXI and bot compact RIO our Compact Field Point?

Q1 only LabVIEW RT

Q2 I drive SEM Servo Motors (http://www.sem.co.uk/) over a Metronix Drives (http://www.metronix.de) using the NI PXI-7358 8 Axis Motion Controller and I Drive Hydraulic Zylinders with Servo Valves over a Hydraulic Servo-Amplifier (ESV24-100-S from http://www.bachofen.ch) also controlled by the same Motion Controller...

The Force Couple from the Motion Controller to the Servo Drives (both electric and hydraulic) is a +/-10V analog Signal from the Motion Controller...

Now there is a new Soft-Motion Motion Controller from NI available. This mean that you can drive a CAN or firewire drive directly as if you would use a real NI HW Motion Controller...

Which weight do you mean :question:

Q3 yes

Q4 I chosed PXI because of the high performance and flexibility (and when we made the decion, CRIO was not awailable)

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Dear Martin

Thank you for your answers

By weight, I mean the force in Newton your motor need to move part of your system

by couple, I mean force Newton.cm

Best regards

Dear Martin

Thank you to give me the precise reference of your servomotor and servo drive

from our side, the motors,

the servo amplifier are PARVEX SBS

and the servo motor are the LX 310 BS

LX 420 CL

I can send you the precise documentation we you give me your personnal email

Best regards

Thibaut

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By weight, I mean the force in Newton your motor need to move part of your system

by couple, I mean force Newton.cm

One Electric Motor has a nominal torque 10 Nm HRS142 (max 30Nm), after the gear we have an 82'000Nm nominal Torque. I don't know the weight but it's a few tons. This motor is used for the yaw (not the same as in the Video).

With another Motor we have a nominal torque 8 Nm HRS115 (max 33Nm) using a "Linear Drive" we can push or pull with up to 3'000 N nominal, (12'400 N max)

The Hydraulic Zylinder has aprox. 20'000 Nm

But you can use the same way for a few N or Ncm...

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is martin@aerodynamics your email adress?

That's a LAVA username, not an email address. That said, contacting a LAVA member directly through their email address without them intviting you to is very bad form, especially if it's something to do with a thread that already exists like this one (you can upload a large file and attach it to the thread). If you must contact a member privtely, us the PM button under their name/details.

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Dear Martin

Find attached the documentation about the servo driver and servo motors

Regards

Thibaut

Salut...

I think you can use this drive with an motion Controller from NI, if you use the Inputs 11/13 with the configuration ST2 (current Mode).

That means that the Input 11/13 is used as an Current Input, and Current = Torque.

The NI Motion Controller (MC) will then control the position, speed, etc. using the analog output.

You don't have to care about the calculation of the correct "current" to achive a position or a velocity, the MC from NI will do that "perfectly" for you...

If there are any other question, just ask...

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  • 2 weeks later...
When using your Servo motion Controller, did you had to use also an Universal Motion Interface (UMI)

Do yo have a documentation describing the interconnection of your system

(The NI Web documentation is very poor concerning the axis controller board I/O

I have used a UMI.

The connection is quite simple,

2 wires +/-10V Analog Output

6 wires Encoder,

Limit Switches

But I look if Ican find a documentation (thuesday)

Dear Martin

Q1) Do you have any documentation about your hardware architecture

Q2) Do you have to use a UMI board?

Best regards

Thibaut

Q1: http://digital.ni.com/worldwide/switz.nsf/...p;node=168640_d

Q2: Yes

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When using your Servo motion Controller, did you had to use also an Universal Motion Interface (UMI)

Do yo have a documentation describing the interconnection of your system

(The NI Web documentation is very poor concerning the axis controller board I/O

I have used a UMI.

The connection is quite simple,

2 wires +/-10V Analog Output

6 wires Encoder,

Limit Switches

Inhibit

Here is the Documentation:

NI 7350 User Manual

http://digital.ni.com/manuals.nsf/websearc...6257180007233A9

Universal Motion Interface (UMI) Accessory User Guide

http://digital.ni.com/manuals.nsf/websearc...62567BD0061DDAC

Dear Martin

Q1) Do you have any documentation about your hardware architecture

Q2) Do you have to use a UMI board?

Best regards

Thibaut

Q1: http://digital.ni.com/worldwide/switz.nsf/...p;node=168640_d

Q2: Yes

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