is right these mesa system config?

I plan to use more than 8 axis so I suppose these config:

mesa 5i24 connected to: 2 mesa 7I65 + 1 mesa 7i46 .... to mesa 7i46 connect 1 or 6 mesa 7i64 (isol i/o). (see attach schemas).

All these board (exept 5i24) uses 5V power input ... I connect these to an external power unit ...

question 1) how many watt can absorbe these config?

question 2) is right these config or there are something of wrong?.



Regards
giorgio

I don't think so, for connecting Mesa smart serial cards like a 7i64 you want one of the rs422 cards like a 7i44

How many axis?
A FPGA card --> 2 or 3 7I52 > 2 or 3 7I83s is probably cheaper and easier to setup (18 axis max)

for example:

5I24 (or 7I80HD for Ethernet) + 2x 7I52 + 2x 7I83 gives you:
12 encoder inputs, 12 analog outputs, 12 analog output drive enables, 10 free serial ports for I/O expansion

5I24 (or 7I80) + 3x 7i52 +3x 7I83 gives you
18 encoder inputs, 18 analog outputs, 18 analog output drive enables, 15 free serial ports for I/O expansion

5I24 (or 7I80) + 2x 7i53 + 1x 7I52 + 5x 7I83 gives you
30 encoder inputs, 30 analog outputs, 30 analog output drive enables, 5 free serial ports for I/O expansion

the targhet is 16 axis analog drive servo AC (enable i/o + analog + encoder) + some i/o digital and after these 1th machine test i plan to add other 16 encoder input as redundancy encoder feedback. But more probabily i stop the work at 1th step so only 16 axis + digital i/o (i think at 16+16 io).

I think is nice have the enable signal in the same board of analogue and encoder signal ... for these reason i see 7i65 ... but i control it price only after read PCW reply.

using 3 x 7i77 is too expensive and I get too many digital i/o I do not need ... I think it's a waste

So the best config for these pourpose (performances/prices) that you can suggest is?

regards
Giorgio

I think the cheapest is

7I80HD FPGA card --> 7I53 + 7I52 --> 3x 7I83 (plus 7I84 for I/O)
= 18 analog channels, 18 enables, 18 encoder inputs, 16 digital outputs, 32 digital inputs
(4 free sserial channels available for I/O expansion)

You might be able to use a 7I93 instead of a 7I80HD but I'm not sure all those encoder would fit
in the 7I93s smaller FPGA

ok for 7i80HD but why is better than 5i24 (these question is for my personal learning)? using ethernet rt is better than use pci or pcie bus? for sure spike problem from pc bus disappear , but in these case performance of motion control is better with pci bus or ethernet bus??

regards
giorgio

PCI/PCIE
+
Faster access 8 KHz or greater servo thread rates on right host
-
Need PC with correct slot type
Hard to get cables out of PC case
Signals share PC ground

Ethernet
+
Electrical isolation from PC/Host
Long distances from PC possible
No slot requirement, works with Mini-PCs and All-In-One flat panels
-
Slower access (1 KHz on most hardware, 4 KHz max on selected hosts)
Needs Preempt-RT kernel (Debians Stretch test ISO image makes this easier)

Note that if you are running a step/dir system or velocity mode analog servo, 1 KHz is usually fine
so the slightly slower Ethernet access is not a real issue.

so .... for simplest project I can use 7i80HB fgpa based .... for strongest 5i24 ... I use only servo ac systems .... that you know for a project of a few axes say max 6 (so i use 7i77E if it exists) can you use a pi3 with rtai with good result (at professional level non-hobby level)? I'm not up to this. From what I know the answer is negative due to high latency and poor performance of rt-ethernet on pi. But I just ask you for updates ... did you make new experiments?

regards
giorgio

I would not say simplest or strongest, the 5I24 and 7I80HD have identical I/O capabilities
The difference is really if you need high servo thread rates, the PCI/PCIE cards are better
for the 2-8 KHz servo thread range

If the standard 1 KHz rate is ok then either PCI/PCIE or Ethernet will perform identically

Typically greater than 1 KHz servo thread rates are needed only for

1. Torque mode drives
2. Very high performance systems

If you have standard velocity mode drives, there is typically little to be gained by faster servo threads

The RPI3 Ethernet is not capable of real time (its piped through USB) nor will it run RTAI
You can run Preempt-RT on the RPI3 though.

about 5i24 & 7i80HD I use a bad expressions ... sorry. You are in right.

1) About rpi3 ... never use for linuxcnc I buy 3 pcs some year ago and use it as motorbike pc ... no other. But I see that some industrial device producer sell it as rt-preemt little plc (with openplc) or little cnc, so I thought that in the meantime things had changed .... in fact I read well and sold it with a real time of 5ms !!! You know if there are some other little cpu board that can use with succes with 7i80HD?

Another thing: but a system of 16 axes each one having the motor running around the 3000rpm and has a feedback encoder of 2500ppr and often have to rotate all 16 (velocity mode), define it as a high performance system or not ? My background does not come from electronics so I am very often in trouble with this kind of thing.

2) Or, for better reply by your side, how many axes at 1Khz rate can I fly at the same time?
And if I need 4Khz rates?

3) after these ... I have seen the characteristics of the 2 cards (7i65 vs. 7i83) ... one has a dac 16bit and the other 13bit. in my mind 16 bit having a clearer definition of the signal, for what I can imagine, means having a more precise positioning ... but in the case of fast movements, such as in puma-type robots, this help performance during full-speed reversals too or not help the "fluid motion" during reversals speed?

regards
Giorgio