firmware 5i25,7i85,8i20 brushless servo drive

I downloaded some firmware, per previous posts on this forum, but I am not seeing the exact combination of boards that I am using. Would someone kindly point me toward the correct firmware, or suggest alternate boards to use on the pncconf wizard.

I am completely new to linux and would like to concentrate my learning efforts in the right direction.

I have a 3 axis mill with brushless servo motors and a MPG. I bought 5i25, 7i85 and 8i20 at the suggestion of the tech guy at Mesa ,over the telephone.

I would like to get one axis working,for now, and worry about the fancy stuff later.

Its unlikely that pncconf will be able to handle this combination of cards
so you will have to start with an example servo hal file and modify it to suit

Peter is right PNCconf doesn"t handle the 7i85 yet and I have never tested the support for the 8i20.

Sorry about that.

Chris M

Thanks for the responses . I will get to work figuring out how to do it manually.

I am surprised that it is not supported. I am pretty sure I used PNC config to start the setup for my 7i85S configuration, but it is a slightly different animal.

The encoder has commutation channel for an 8 pole motor. I replaced the original Fanuc encoder with a Danaher, Dynapar series f15 2048 ppr. and index pulse. It cost about $210.00. I only bought one. If it works I will get 2 more.


I did see a video, on the enc- users- request e-mail list , of someone using a standard fanuc encoder but I have no idea of how they did it.

AFAIK there are at least 4 types of Fanuc encoders:

1. Incremental quadrature
2. Absolute quadrature
3. Incremental serial (Ai64 for example)
4. Absolute serial (Aa64,Aa1000 for example)

Type 1 is a standard quadrature encoder, the only non standard thing is that they use a 4 bit absolute position code instead of the more common 3 bit Hall signals

Type 2 is the same as type 1 except that it has a request pin that causes the encoder to send the absolute position (in quadrature) when pulsed (these require a backup battery to retain the absolute position information)

Type 3 is a serial encoder that sends absolute position as a serial bitstream when requested by the host.
the absolute position is volatile so lost when power is removed and so not valid until an index has been detected.

Type 4 is like type 3 but has the absolute position stored in battery backed memory so does not forget position when main power is removed. Surprisingly these encoders keep count on battery power even if moved when main power is off.

Both type 3 and type 4 encoder have a 10 bit absolute commutation track that does
not depend on main or battery power (its always valid)

I'm pretty sure all types can be supported but the interface hardware and firmware differs based on encoder type. Quadrature types use standard differential quadrature interfaces, serial types use a RS-422 interface (7I85,7I74 etc). The serial encoders need the FAbs firmware module and this is only supported in LinuxCNC master. As Andy mentioned, his BLDC comp can use the Fanuc type commutation signals
from the Fanuc quadrature encoders for commutation startup.

I think that it would be way too complicated for me to try and use the Fanuc encoders. I can"t even figure out how to use the ini file that PCW kindly sent me, in another thread.

I did use one of Pico Systems Fanuc encoder converters to run one of the motors on the bench , But that was three years ago and it seems that I have forgotten everything that I learned about linux at that time.