Connecting to a device console using screen shows no output I am trying to access a network device console from my mac using a Prolific Technology USB-serial adapter to the device's console. After installing the relevant driver, the adapter is correctly shown:
$ ioreg -p IOUSB -l
... 
    +-o USB-Serial Controller@14200000  &lt;class AppleUSBDevice, id 0x10000034a, registered, matched, active, busy 0 (101 ms), retain 11&gt;
    |   {
    |     &quot;sessionID&quot; = 1402970206
    |     ...
    |     &quot;bDeviceSubClass&quot; = 0
    |     &quot;bcdUSB&quot; = 272
    |     &quot;USB Product Name&quot; = &quot;USB-Serial Controller&quot;
    |     &quot;PortNum&quot; = 2
    |     &quot;non-removable&quot; = &quot;no&quot;
    |     &quot;IOCFPlugInTypes&quot; = {&quot;9dc7b780-9ec0-11d4-a54f-000a27052861&quot;=&quot;IOUSBFamily.kext/Contents/PlugIns/IOUSBLib.bundle&quot;}
    |     &quot;bDeviceProtocol&quot; = 0
    |     &quot;IOUserClientClass&quot; = &quot;IOUSBDeviceUserClientV2&quot;
    |     &quot;IOPowerManagement&quot; = {&quot;DevicePowerState&quot;=0,&quot;CurrentPowerState&quot;=3,&quot;CapabilityFlags&quot;=65536,&quot;MaxPowerState&quot;=4,&quot;DriverPowerState&quot;=3$
    |     &quot;kUSBCurrentConfiguration&quot; = 1
    |     &quot;Device Speed&quot; = 1
    |     &quot;USB Vendor Name&quot; = &quot;Prolific Technology Inc.&quot;
    |     &quot;idVendor&quot; = 1659
    |     &quot;IOGeneralInterest&quot; = &quot;IOCommand is not serializable&quot;
    |     &quot;IOClassNameOverride&quot; = &quot;IOUSBDevice&quot;
    |   }


To access the console, I started screen from Terminal as per below:
$ screen /dev/tty.usbserial 9600

When I power on the connected network device, I can see the cursor bounces around randomly as if responding to the device console output, however no characters appear on Terminal at all. I know the USB-serial adapter is working fine, as using it on a Windows machine, I am able to access the same network device console without any issue. Any idea how to address this?
Thank you.
Since I couldn't get this working on my mac after multiple days, I decided to try my luck with a Debian 9 VM running in VMware Fusion within this mac. As soon as I made the device available within Debian VM, it was automatically detected and an associated tty* device was created:
# lsusb
Bus 002 Device 002: ID 0e0f:000b VMware, Inc. 
...
Bus 001 Device 005: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port
...
$ ll /dev/ttyU*
crw-rw---- 1 root dialout 188, 0 Dec 29 14:30 /dev/ttyUSB0

Unlike /dev/tty.usbserial within macOS which was open for group others, device /dev/ttyUSB0 wasn't. So, I started screen with sudo:
$ sudo screen /dev/ttyUSB0 9600

And voila, it worked, as per the following screenshot!

I guess this is still a workaround. Checking the screen status (Ctrl-a + Ctrl-i (macos), Ctrl-a + i (Linux)), the latter had CD in brackets, implying signal CD was in effect:

That is the only significant difference that I could spot. Hope this helps others.