Does the 7i92-7i76-7i74 firmware support SSI ?

Hi

Does the 7i92-7i76-7i74 firmware support SSI ?
I need to connect 6 absolute encoders.

Or I need special version?

How many ports support SSI in this configuration ?

Thanks!
Dmitry

There's no standard firmware for this but it should be easy to cobble together.
As far as SSI channels go, I'll have to see how many fit.
I'll try to get to this today or tomorrow sometime.

freeby.mesanet.com/7i92_7i76_7i74_ssid.bit

8 SSI channels fit without a problem
( I was probably thinking about BISS which is substantially larger than SSI )

PCW,

Thank you for support!

Dmitry

Hi, PCW

It's hard to find firmwares with ssi support. They are not included into Support software packs and can be only found at some rare posts at the forum (with secret links to freeby.mesanet.com/something_ssi.bit ).
Are there any for 5i25+7i77 (+7i74) and 7i92+7i77 (+7i74)?
Most of times I'll need 3-6 ssi encoders but sometimesonly 1 will be enough.

Its not a common config but I can make them, I'll try and get to this sometime this week.

freeby.mesanet.com/7i92_7i77_7i74_ssid.bit
7I77 + 8 SSI channels on 7I74

Thank you very much! I'll gona try it this week.

Hi, PCW!

Can SSI channels work in Slave mode, acting as a „listener“ to the existing data communication between encoder and servo amplifier?
It's a big problem to connect absolute encoder of servo to amplifier and to 7i74 simultaneously

Maybe it needs change only two bytes of code

Thanks!

Sorry for my English

With hope
Dmitry

It should be possible to do this but its awkward for a number of reasons:

1. isolation/noise: The drives encoder interface is often a much noisier environment than the drives host interface
its not really intended that these signals be tapped at this place

2. You would need 2 differential receiver interfaces without termination (not a problem but awkward wiring wise with a 7I44/7I74)

3. The servo drives encoder interface is asynchronous to LinuxCNC's sampling leading to beats and problems with
velocity estimation ( without added hardware to timestamp the servos reads )

4. Drives with absolute encoders usually have a way to read this absolute position