Experimental Physics and
Industrial Control System

Jörn Dreyer via Tech-talk <tech-talk at aps.anl.gov> · Mon, 03 Jun 2024 06:46:32 +0200

Hello Baeg,

Am Montag, 3. Juni 2024, 02:12:54 MESZ schrieb whitetiger1123 via Tech-talk:
> Hello all,
> 
>  
> 
> We’d like to use OMS MAXnet controller to control motor stage.
> 
> Currently, we are using MAXnet as RS232 communication by connection MAXnet controller to PC, which is a centos PC server.
> 
> We trying to add one more MAXnet controller to the PC, what we are using right now. (without the PC’s expansion)
> 
> I want to do the same RS232 communication, is it possible to connect 2 MAXnet controllers to 1 PC for different serial communication?
> 
> If possible, can I add 2 different serial communications code to the serial part of MAXnet.cmd?
> 
>  
> 
> # Serial
> 
> drvAsynSerialPortConfigure("MAXNET1","/dev/ttyUSB0",0,0,0)
> 
> drvAsynSerialPortConfigure("MAXNET1","/dev/ttyUSB1",0,0,0)
> 
> Like this?
from the EPICS point of view thats how you do it. But....

you have to keep in mind that Linux on the next reboot of the machine might change the order of the serial interfaces when using USB to serial adaptors.
So what is now named ttyUSB0 might become ttyUSB1  and vice versa.
To prevent this you have to do some udev tricks and force the system to use always the same device name for the same hardware.
For that you will need to find out if the USB2serial adators have a unique key like a serial number. Most of the cheap USB adaptors use the FTDI chip
which in principal can gat a unique serial number but most harware vendors do not implement that!
Even having two adaptors from different vendors might not be distinguishable because of that "feature".
And the USB bus number is not a uniue key as it depends on in which USB port the adaptor is plugged in.

My recommendation would be to take two small SBC e.g. RaspberryPi and connect each MAXnet controler via a USB2serial adaptor to its own SBC.
That way you circumvent the above mentioned problems.

Regards,

Jörn
> 
>  
> 
> I’m asking you questions to use MAXnet efficiently,
> 
> Please give me a lot of advice..
> 
>  
> 
> Sincerely,
> 
> Baeg.

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System