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Motor selection help
JCG77
01-11-2016 02:56 PM
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HI all,
I'm looking at purchasing two NEMA 23, ST23-7E, with product number 7840342-03 and SMD 7620 motor drive. Do I need two motor drives? Is the motor direct drive or is it gear reduced? Do I have the option of an absolute encoder or must it be an incremental encoder? What is the resolution of the encoder and other specs?
Thank you kindly,
James
01-11-2016 03:06 PM
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Hello all, I am soon going to be ordering a NEMA 23 ST23-7 stepper motor with encoder. Can anyone tell me what type of encoder this is? Is it an absolute encoder? When I purchase the motor do I have the option of having an absolute encoder? It would make the project I'm working on easier if it were. Thanks
Buechsenschuetz
01-12-2016 03:11 AM
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The data sheet says clearly that the motor can be ordered with an INCREMENTAL encoder.
It is possilble to use absolute encoders directly on the motor shaft, however, there is a problem with the number of turns you want to do. Of course you cannot count any number of turns with an absolute encoder.
If you need absolute position detection, there are magnetic encoders available. They work with a tape with tracks magnetized with a special pattern which is glued on one part of the system and an encoder head. In many cases the (usualluy flexible) tape can be attached to the circumference of a round part, too. But the output of these encoders is not compatible with the NI motion controllers, they use special data protocols to transfer the position information.
01-12-2016 08:23 AM
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Thank you,
Do we know the resolution of these incremental encoders? Or any other information on them?
Thanks
01-12-2016 01:09 PM
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Greetings,
If you take a look at the datasheet, seen below, you'll find that the resolution is 1000 counts/revolution.
http://www.ni.com/datasheet/pdf/en/ds-311
The number of drives you'll use depends on the type of drive you're using. If you take a look at the link below, you'll see that there are options for 1, 2, and 4 axis drives, meaning they can control that many motors.
http://sine.ni.com/nips/cds/view/p/lang/en/nid/3308
Applications Engineering
National Instruments
