Bitfile or help – Mesa 6i25 + 7i74 (BiSS-C) + 8i20 + 7i70/7i87

Hello,I am new to LinuxCNC and Mesa hardware and I am working on a relatively large project. Before going further, I would like to ask for advice to make sure I am approaching the configuration correctly.
I am on a linux 4.19.0.21 -rt - amd64 smp preempt rt debian.
My hardware configuration: Mesa 6i25 (PCIe) Connected via P3 (external connector) to a Mesa 7i74. It is intended to interface a signal BiSS-C from a RAIK060 BiSS-C rotary encoder used for motor position feedback. A mesa 8i20 Powerdrive for the motor associated with the BiSS-C encoder. A mesa 7i70 and a mesa 7i87 are used for another part of the project: Temperature sensor, Pressure sensor and one servo motor.
II am planning to build a custom wiring setup using a RJ45 cable to carry the BiSS-C signals. To connect this cable to the first RJ45 port on the 7i74.
Current status: I have tried modifying an existing VHD file as a starting point, however I am not confident that the overall architecture is correct or my intended usage. What I am looking for is general guidance on the recommended architecture for this combination of cards ( a bitfile would also be perfect ) any advice on a suitable firmware for the 6i25 + 7i74 (BiSS-C), any pitfalls to avoid or best practices for a setup of this size. I understand this is a complex setup for a beginner, but I would need help and be thankful for your time and help.

Bitfile (and changed source)  for 5i25/6i25 with 7I74 and 4 sserial channels and 4 BISS channels:

 

Pretty sure Tommylight has some example files using SSI feedback (which is very similar at the HAL level)

Thank you for your help, I'll check that right away.

Hello again, I was sick for a week, so I didn't make much progress.
My boss want a change in our configuration, he want to replace the 7i70 by a 7i76 connected on the port p2 from the 5i25. I wanted to know if it need a change in the bitfile or if i can use something existent like the file "5i25_7i76_7i74biss3d" that you (PCW) provided here: forum.linuxcnc.org/24-hal-components/551...-biss-encoder#320220?
I tried to read and to understand what was in the vhd but i am not good enough for making it myself...

In order to experiment i already tried to used this existing bit file "5i25_7i76_7i74biss3d" in addition to an existing hal (the two are not from the same project) but i have an issue. When i tried to modify my hal in order to use the two serial port like this:
loadrt hm2_pci config="num_encoders=0 num_pwmgens=1 num_stepgens=5 sserial_port_0=0x00xxxx sserial_port_1=0XXX"
with p3 => 7i74 = 0 => bissc 3 => 7i87
et p2 => 7i76.
In my understanding my hm2_pci config should be correct and be followed by : hm2_5i25.0.7i76.1.0.input,  hm2_5i25.0.7i74.0.0.something and hm2_5i25.0.7i74.0.3.otherThing? But i get an error: hm2/hm2_5i25.0: num_serials references 2 instances, but only 1 are available, not loading driver ...etc
I dont know if the issue came from the bit file or from the hal.

In the meantime, I will continue reading the hal manual.
Once again thank you for your help!

The error is a hal error, there is only one sserial port in that configuration.

BISS is not related to sserial and is set up differently in the hal file.

The hostmot2 man page describes the driver command line for BISS devices.
Unlike sserial devices, BISS devices are not "discoverable" so need to be setup
with device specific data in the driver command line.

man hostmot2

and scroll down to the BISS section.


 

Ok so i progressed a bit But my raik060( biss-c/ssi signal) need a master clock in order to operate

(BiSS-C / SSI):  DESCRIPTION:                           WIRE
VCC                 Power supply input Power         Red
MA+ / CLK+    Positive clock input                  Orange
MA- / CLK-         Negative clock input              Yellow
SLO- / DATA-     Negative data output             White
SLO+ / DATA+  Positive data output               Green
GND                  Ground Power                        Black
 
and i get some contradictory information. i read somewhere that only a 7i85 card could generate a clock and not other card like 7i76 or 7i74 ? if it is true that mean i have to rethink ma configuration.

For now i have added this to my main hal and it seams to be good, at least it don't crash

ps i am reading tommylight post for the conf in hal file, it look promising!

Update, i just received the (almost) final plan for this project.
mesa part:
  6i25 => 7i76  -> spindle   = 1 motor
                        - >field output 1 = motor on/off
                        - >field output 2 = motor on/off
                          ? -> encodeur biss-c ?
          => 7i74   ? 0 => encodeur biss-c (RAIK060 by vishay) ?
                         1 => 7i87 -> 6 temperatures captors
                                          ->  1 pressure captor
                         2 => 8i20 -> main motor
Encodeur:
- i use an encoder raik060 from vishay (doc bellow) it seem to need a clock from the master card and maybe a signal? start?? in order to operate.

Project non mesa part.
This project is not a cnc but a system to test pieces it is composed  of 2 part:
- The first part is 1 motor cyclic powered by 8i20 in team with the biss-c encoder and a pressure captor in team with the motor controlled by 7i76 spindle

- The second part is the cooling system that will work in continue.
this is 2 motor that will run full time en 4 temp captors for security

QUESTIONS:

-Concerning the signal biss i am flexible on what part to use, ether the 7i76 or the 7i74 depending on what may be possible or the easiest and i saws where was an encoder part on the 7i76U  was curious if it was possible to use that?.
-If we keep the signal biss-c on the 7i74 it is important to note that i need to have most of the 7i74 port to work normally and only the port 0 has a biss-c socket. If it is not possible i can use a second 6i25 and 7i74 dedicated to handling the signal biss.
- i still dont have any signal from or to my encoder, is their something to do in order to generate the clock signal or to make it react? I cant seem to find details about this part in the forum (i still have a lot to read so i am not loosing hope) and chatgpt or other ai keep telling me that it is impossible or to use non existing  driver like hm2_biss.

I added the doc of the encoder i am using, it is the Multi turn version, information about the signal are page 15 and 16.

Lastly is there any doc about how to configure a framework? Even if i cant do one myself, knowing what is happening would help me to know what information i need to give in order to get a bitfile adapted to my configuration.

Any daughtercard that provides a RS-422 interface will work for BISS

With your 7I76 + 7I74 configuration, the BISS interface could either be on the one RS422 interface on the 7I76 or
any of the eight RS-422 interfaces on the 7I74 depending on the firmware.