I know there are similar posts on this topic, but I've scoured them all and haven't been able to figure this out. I'm trying to control my projector via a R232 port. I have a USB to R232 cable, specifically this one.
That's using the PL2303 chipset for RS232. I can't seem to get it to register anything on my Pi.
pi@raspberrypi:~ $ dmesg | grep tty [ 0.000000] Kernel command line: coherent_pool=1M 8250.nr_uarts=1 bcm2708_fb.fbwidth=656 bcm2708_fb.fbheight=416 bcm2708_fb.fbswap=1 smsc95xx.macaddr=B8:27:EB:25:6C:54 vc_mem.mem_base=0x1ec00000 vc_mem.mem_size=0x20000000 dwc_otg.lpm_enable=0 console=tty1 root=PARTUUID=f991b5bc-02 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait [ 0.001276] console [tty1] enabled [ 1.062493] 20201000.serial: ttyAMA0 at MMIO 0x20201000 (irq = 81, base_baud = 0) is a PL011 rev2 [ 1.070613] 20215040.serial: ttyS0 at MMIO 0x0 (irq = 53, base_baud = 31250000) is a 16550 [ 16.242115] usb 1-1: pl2303 converter now attached to ttyUSB0
I've copied some python scripts to write to ttyS0 and read from ttyUSB0. I'm apparently able to write to ttyS0 but cannot read anything from ttyUSB0.
Even if I do
echo "hi" > /dev/ttyUSB0 cat /dev/ttyUSB0
I get nothing.
I have serial login disabled.
Is there a way I can determine if, for example, this device is defective?