Mesa 7i33 Encoder Input

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18 Jan 2010 13:33 - 18 Jan 2010 14:18 #1548 by BigJohnT
In the Mesa 7i33 you get a choice of using TTL mode or RS-422 mode. How do I tell what mode to use other than the RS-422 can count faster?

I'm working on a Hardinge CHNC 1 retrofit so everything is 24vdc. Do I use the +5V pin on the TB to power up the encoders or 24 volts from the power supply?

Edit: I just found on the cable list that they get 5V and 0V on 4 of the connections.

Thanks
John
Last edit: 18 Jan 2010 14:18 by BigJohnT. Reason: Found More Info

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18 Jan 2010 16:40 #1551 by PCW
Replied by PCW on topic Re:Mesa 7i33 Encoder Input
Depends on your encoders.
If your encoders are differential (RS-422), they will have 8 wires total (or 6 if they have no index)
and should be run in RS-422 mode. TTL encoders would have just 5 or 4 wires total
In both cases a separate shield wire may be present as well.
I think it would be rare for professionally built machine to use TTL encoders
as they are so much more susceptible to noise than differential encoders.

As far as power goes if the encoders will draw more than a few hundred mA
its best to power the 7I33 from a separate 5V supply and not depend on the flat cable.
If you have a 5I20, the best source is the 5V terminal block on the 5I20

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18 Jan 2010 18:00 #1552 by BigJohnT
Replied by BigJohnT on topic Re:Mesa 7i33 Encoder Input
Peter,

Thanks for that info. I'll try and find out the draw on the encoders. I have the model and serial numbers of all of them in my documentation. They have about 10 or 12 wires as I recall ( I'm not near the machine). The have two +5v and two 0v lines tied together (+5 to +5 and 0v to 0v) and two wires each for A, B, and X and a couple that are not used. So it sounds like RS-422 for me. Thanks again for the heads up on the power draw. Oh, and they are all Heidenhain encoders with the X and Z connected directly to the ball screw.

Thanks
John

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18 Jan 2010 18:33 #1553 by BigJohnT
Replied by BigJohnT on topic Re:Mesa 7i33 Encoder Input
The encoders have

5VE
5VL
0VE
0VL
PA
PA (with a line on top)
PB
PB (with a line on top)
PZ
PZ (with a line on top)

So I assume at this point that the connections between the encoder and the 7i33 is
PA - ENCA0
PA (with the line over it) - /ENCA0
PB - ENCB0
...

Thanks
John

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18 Jan 2010 19:42 #1554 by BigJohnT
Replied by BigJohnT on topic Re:Mesa 7i33 Encoder Input
I found out some more info on the Heidenhain ROD 426 encoders

Output signals - 5v TTL Quadrature
Line count - 50 to 5000
Mech. perm. Speed - 12000 rpm
Power supply - 5 V
Scanning frequency - Max. 300 kHz

Looks like 120mA Current con. without load what ever that means.

It also has this

Incremental signals TTL if that means anything.

Here is the link to the pdf

www.atechauthority.com/products.asp?id=174

Thanks
John

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19 Jan 2010 02:05 #1556 by Zig
Replied by Zig on topic Re:Mesa 7i33 Encoder Input
Mesaa 7i33 is a godsend. I am interfacing an RFS Elektronik glass scale made by RFS Elektronik ( part of Haidenhain of late). I had visions of having to build rs-422 receivers but with 7i33 no worries.

I would recomend 7i33T with its screw terminal arrangement in preference to the 50 way ribon cable ( wish i paid more attention to options).

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19 Jan 2010 12:03 #1558 by BigJohnT
Replied by BigJohnT on topic Re:Mesa 7i33 Encoder Input
I think the T option has been repaced by the TA and thats what I purchased.

John

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