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While I probably still have some (very) old serial cables lying in a box somewhere from when Kermit and zmodem were a thing, I no longer have a computer with a DB9 port.

So its now a USB-DB9 serial cable from Amazon.

Unfortunately, and it's making me feel like a total noob, I can't get a useful terminal session to work from Linux.

I'm using minicom on Linux Mint/Debian Jesse. 8N1 and 115200.

The only time minicom shows a response from the switch is after I send a Hangup sequence. Type something, send Hangup, type some more, send another Hangup... This shows that there is some communication but it is not useful.

It's been a while but I've done enough with serial connections in the past that something seems off. And I'm pointing the finger at the serial cable as I can't get it to work when connected to a few different devices.

So, are there some USB-DB9 serial cables that work and some to avoid due to chipsets or other things?

'lsusb' displays the following for the cable in question: (The verbose output is below.)

Bus 002 Device 005: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC

Thanks
Mark

(grrr... the heiriarchal indenting is lost when I paste the output..)

Code: Select all

# lsusb -v -d 0403:6001
Bus 002 Device 005: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Device Descriptor:
 bLength 18
 bDescriptorType 1
 bcdUSB 2.00
 bDeviceClass 0 (Defined at Interface level)
 bDeviceSubClass 0
 bDeviceProtocol 0
 bMaxPacketSize0 8
 idVendor 0x0403 Future Technology Devices International, Ltd
 idProduct 0x6001 FT232 USB-Serial (UART) IC
 bcdDevice 6.00
 iManufacturer 1 FTDI
 iProduct 2 FT232R USB UART
 iSerial 3 AK05D2XC
 bNumConfigurations 1
 Configuration Descriptor:
 bLength 9
 bDescriptorType 2
 wTotalLength 32
 bNumInterfaces 1
 bConfigurationValue 1
 iConfiguration 0
 bmAttributes 0xa0
 (Bus Powered)
 Remote Wakeup
 MaxPower 90mA
 Interface Descriptor:
 bLength 9
 bDescriptorType 4
 bInterfaceNumber 0
 bAlternateSetting 0
 bNumEndpoints 2
 bInterfaceClass 255 Vendor Specific Class
 bInterfaceSubClass 255 Vendor Specific Subclass
 bInterfaceProtocol 255 Vendor Specific Protocol
 iInterface 2 FT232R USB UART
 Endpoint Descriptor:
 bLength 7
 bDescriptorType 5
 bEndpointAddress 0x81 EP 1 IN
 bmAttributes 2
 Transfer Type Bulk
 Synch Type None
 Usage Type Data
 wMaxPacketSize 0x0040 1x 64 bytes
 bInterval 0
 Endpoint Descriptor:
 bLength 7
 bDescriptorType 5
 bEndpointAddress 0x02 EP 2 OUT
 bmAttributes 2
 Transfer Type Bulk
 Synch Type None
 Usage Type Data
 wMaxPacketSize 0x0040 1x 64 bytes
 bInterval 0
Device Status: 0x0000
 (Bus Powered)


Are you sure your using a NULL serial cable?

It is one of the USB-DB9 serial cables with a FTDI Chipset.

See: https://www.amazon.com/gp/product/B01GA0IZBO/

First thing I would do is check your flow control settings in minicom if it's acting like that.
It also may not be an actual null model setup - could just be the correct gender

Used to always use FTDI but in recent years have had some problems in Linux so switched to these using a null modem cable: https://www.bhphotovideo.com/c/product/ ... erial.html

I know they work on Ubuntu, and seem to remember using them on Raspbian Jessie as well.


Edit: Bus 001 Device 003: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port

Perfect!

Just what I was looking for, a cable that is known to work. Thanks!