Okuma Servo Drives
- Diederik
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I have a Okuma LB15, with Okuma servo drives. I attached the electrical drawings of the machine, and you will see on page 24, (W1500-555-232) it has the XB1-1 and XB1-2 connections for the command signals. This is unfamiliar teritory, but something that I would like to learn, and know how it works. I believe this is serial communication, and from forums, I understand that this is possible with smartserial communication ( I believe it should be similar to the 8i20 communication?). I need guidance as to what Mesa cards will be able to handle these signals. ...? If there is any?
Signals: Clock
Clock-K
Ser DATA-N
Ser DATA
Strobe
Strobe-N
Are these signals that can be controlled from Mesa cards?
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- andypugh
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The first thing you will need is some information about the data packet format of the drives.
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- Diederik
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Thanks for your reply. I appreciate your input.
So... My thinking: It might be easier to just rather replace the servo Drives...? I think all the time that might go into the researching of how this works, might ... possibly ... cost me more time, tears and frustration, which costs more than just replacing them?? It's a pitty. I believe these drives is quite capable, and reliable. It would be awesome if there could be some type of interface, that can convert the analog signals to the okuma digital communication. Like a analog to digital converter. Have anyone ever heard of something like that that is available for these Okuma drives?
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- emcPT
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- andypugh
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What type of motor and encoder do they use?
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- Henk
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I looked at this for Diederik and came across some info on the web
cncmanual.com/okuma-drive-units-bl-ii-d-...-maintenance-manual/
s3.amazonaws.com/Icarus/DOCUMENTS/Okuma_Manuals_3695.pdf
I briefly scanned through them but couldn't find any detail about the data packet format. It is possible that I have missed it and I will have a better look over the weekend, but I have a feeling that that info is not included.
The motors are fitted with absolute serial encoders. these encoders communicate with the SVP board which sends a current command to the Servo Amp (BL IID).
The pulse handle (mpg I assume) also connects to the SVP board.
I have a feeling that the position loop is actually controlled by the SVP board and that the main board only sends the commanded position to the SVP, but I may be mistaken.
Sadly, I don't think it is worth pursuing this option unless we can find the detail on the serial communication, but hopefully someone out there can assist with this detail
Henk
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- emcPT
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A conical shaft was made that fits on the motor shaft and on the incremental encoders. They were standard 3 phase AC servos.
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- andypugh
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What is the power rating of the motors? I am wondering if this would be a good fit for the STMBL drive (which also closes the position loop in the drive, and handles a wide range of feedback system. An extract from the docs:
Currently supported command interfaces are:
Mesa Smart-Serial
Step-Dir
Quadrature
Serial
+/-10V control is not supported, though the hardware capability exists.
Currently supported feedback interfaces are:
Encoder
Resolver
sin/cos 1vpp
Hall sensors
Mitsubishi absolute encoder
Yaskawa absolute encoder
Sanyo Denki absolute encoder
Fanuc serial encoder
The hardware has the capability to support other protocols like:
EnDat
BiSS
SSI
Modbus
Profibus
Hiperface
CANopen
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- Henk
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The existing drives are rated 50A and 100A respectively for X and Z.
Maybe Diederik can post a photo of the motor nameplates.
Henk
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- andypugh
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I have used the Mesa 8i20's before and I believe the STMBL drives are similar, but I don't think they are big enough for these motors.
8i20 is a "dumb" drive and STMBL is a smart drive, though they both work well with LinuxCNC and use smart serial (I actually have a machine that uses 3 x 8i20 and 1 x STMBL)
But yes, depending on the power IC fitted the STMBL can handle up to 20A. 100A for Z seems pretty excessive, that's something like 20kW?
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