Hi,
I've downloaded a copy of the CSMIO/IP-A manual.
I would use the 24V power supplies provided within the servo drives.
You have two servos each with its own 24V supply. It is highly likely that they will be the same but if they are not and you connected them together,
that is 0V to 0V and 24V to 24V and they are not identical they could fight each other, I would not recommend it.
I would instead use the 24V supply from one drive to power one of the photo transistor clusters of the CSMIO and use the second 24V from the other drive
to power a second but separate cluster. From page 27 and 28 if you hook the 0V and 24V outputs of one drive to pins 14 and 1 respectively of the DB25
Output connector of the CSMIO then outputs 0-3 of the CSMIO can signal inputs to the drive. In reality you probably only need one, an enable. You
could use others if you were attempting position or velocity indexing but as you are not the will be three unused outputs in that cluster.
With that arrangement the CSMIO output sources current per page 28. That would hook to the anode of the input photodiode of the drive input and the catode
would hook to 0V of its own drive.
In like fashion the 0V and 24V of the second drive would hook to pins 17 and 4 respectively providing supply for outputs 4-7. One of which would be hooked to
the anode of the input photodiode of your selected input of the drive, the cathode would hook to 0V.
Note that the outputs of the CSMIO are current limited but it looks like the current limit is 250mA, rather too much for a photodiode input. Its likely that the photodiode
input has a current limiting resistor in circuit, if not an external resistor will be required. About 5kOhm with a 24V drive will cause an active photodiode current
of about 4mA which should be enough to reliably signal across the opto barrier and still retain a sufficiently low impedance to not be noise prone.
That arrangement allows the outputs of the CSMIO to signal to the drive inputs.
Now consider the reverse. You will want at least one digital output form the drive, a fault signal. You may in fact want more than one. I have not studied
the Lexium manual but I suspect much like my Allen Bradley servo there are a number of fault conditions which can be signaled independently.
Given that you are using the CSMIO to close the position loop then you will not be concerned with a 'following error' fault from the drive. The other
two commonly signaled faults you may wish to handle separately. 'Over current' has a similar meaning to 'following error', when the commanded position
varies widely from the actual position the servo loop attempts to apply a large correction and correspondingly large current. The second fault is 'overvoltage'
which is a the primary indicator that the commanded deceleration exceeds the drives ability to absorb the braking energy. There will be other faults generated by
the drive including overheat and out of limits if so programmed but they are usually combined into one fault output.
I would again make use of the built in 24V supply of the drive. Using Type 1 logic of the previous pic:
connect the phototransitor collector (drive output) to the cathode of the CSMIO input photodiode, IN0-, pin 14, as an example, and the 24V supply of the drive to the anode
IN0+, pin1 per page 23. It would appear that there is a current limit diode in the input circuit of the CSMIO so you need not concern yourself with an external
resistor. You will have to repeat this, ie two wires to each of the CSMIO inputs you require. Make sure that the supply sourcing the output current is returning to the
same supply. That is do not use the X axis drive to supply output current for a Z axis output.
Craig