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Using serial commands to control 8-axis servo system with PCI-7358?

Hello,

I am currently developing an 8-axis brushless servo system that I would like to control using LabView software and the PCI-7358 controller. I will be using Danaher Motion servos and drives, which I would like to connect to the controller via two UMI-7764s.

However, I do not want to create any motion profiles with Motion Assistant/LabView. Instead, I would like LabView to read in serial commands from another computer running a simulation program that will generate and transmit motor commands via a RS-232/422 port. The simulation will be controlled by a series of joysticks, so the program will be operating in real-time.

My question is this: is this idea feasible and what type of data would be best to send to LabView so that it can most easily convert the incoming data into motion commands? Also, how fast should these commands be coming in? I'm not on the software side of this project, so I'm not too knowledgeable about their capabilities. But I do know that they have the simulated motor velocities, accelerations, etc. which they can send out in any way necessary.

Also, is it possible to output and duplicate the incoming incremental encoder outputs to multiple sources using the digital I/O ports on the controller? What hardware would I need to accomplish that? I've been looking at the SSR modules but I'm not sure how those work exactly.

Thanks for your help.

-Joey
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I'm not real clear on all you are trying to accomlish, but I think you might be better off with a stand-alone controller.  Galil, Delta Tau, Aerotech, and others make 8 axis controllers that accept ascii serial commands and/or have Labview and ActiveX drivers.  You will not get real time over the serial port.  You might get close to it with Ethernet or USB, though.
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Here's a quick summary of what I'd like to do...

We have a computer running a custom-built simulator of an off-shore cargo crane which takes in joystick commands from a command chair. It then passes these on to other hardware which takes in information about the ship and crane components movements and calculates new joystick commands which reduce the swing of the cargo while still moving it in the desired direction. This system is implemented using hardware-in-the-loop techniques, namely the crane's actual crane controller box. The crane controller and the swing reduction hardware both need inputs from all of the motor encoders. Right now this is done with encoder emulating circuits, but it's not reliable. Therefore, we're creating a hardware solution by emulating the crane motor motion with small servo motors attached to encoders. The simulation software will tell the motors what to do, and their respective encoder signals will be passed on to the appropriate hardware.

We would like to use something like LabView so that the motion controller and software can be adapted for other projects as well. Ethernet/USB would work as well, but I would still need to know what to send to LabView to make this as streamlined as possible.

A stand-alone solution will probably be a last-resort option.

Thanks!

-Joey
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OK, it is becoming a little clearer.  The NI hardware is being used as a simulated load?  The "new" joystick commands are what get passed on to the motion controller?  I am still not clear where Labview is being used.  What is the form of the "new" joystick commands?  Is this analog or serial comms? 
 
If you need to split your encoder signals to 2 devices, Encoder Products Company makes a splitter, as does Baldor.  You may want to be careful of your wording, because you refer to sending signals to motors.  This could be interpreted as sending commands to the motion controller or to the drive.  We are almost there, so if you give a little more information we may be able to come up with a solution.
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LabView will be used to take in serial commands from the simulation computer and convert them into motion commands using NI-Motion VIs which will pass them to the PCI-7358 which in turn sends them out to the Danaher drives and servos. The simulation computer won't output joystick commands to LabView but, rather, velocity and position data for each axis which LabView will input into the NI-Motion VIs. The motion induced by the PCI-7358's commands to the drives will then turn the motors/encoders, and then that data will be sent back to the drives, the controller and a couple other pieces of hardware.

-Joey
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Are the serial commands already determined, or can you make those whatever they need to be?  Unless you are using absolute encoder, and I don't think you are, you will have to somehow coordinate the zero position with all of the devices if you are only sending back encoder pulses.
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The serial commands can be programmed to be whatever LabView needs them to be. The simulator software will calculate each axis' velocity, acceleration and position, so it can relay that information to LabView in whatever format necessary.

As for coordinating zero positions, each axis will be equipped with an incremental encoder built into the servo and an absolute encoder attached the servo with a flexible shaft coupling. This is because the additional hardware in this system needs both incremental and absolute SSI (binary) encoder signals to function. So I supposed the absolute encoders could be split as well and be run into the controller instead of the incremental signals. However, I talked to a NI engineer the other day and he said that NI-Motion doesn't read in absolute signals. Any truth to that?

-Joey
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I believe that is true about the absolute encoders and NI hardware.  I don't know of a way to split an absolute encoder signal.  Again, I think you could streamline things by going to a stand-alone controller.  You won't need Labview or the PC for the card.  If I were you, I would call Delta Tau.  I'm sure they would have a solution for this.  There is a pretty steep learning curve with them, but they are very capable.
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