View source for Scanserial

{{todo| InProgress (11.04.2015-12:17->MD+)|Mike Dean| project=OE 5.0,MD,InProgress }}
{{#seo:
|title=scanserial
|titlemode=append
|keywords=
|description=Using scanserial to find your serial ports.
}}

<!-- /*********************************************************************************************************/ -->
<!-- /****************************************  Page Description Text  ****************************************/ -->
<!-- /*********************************************************************************************************/ -->
EMAC provides a tool named <code>scanserial</code> to assist a user in finding out which device nodes on a computer correspond to its serial ports, and to assist in finding out which particular device node corresponds to a particular serial port.  The <code>scanserial</code> tool was created because no existing tool provides this functionality in a convenient way.  Other methods for determining this all require a slow trial and error approach.

This guide walks the reader through the steps required to perform these tasks using the EMAC <code>scanserial</code> tool.

__TOC__

<!-- /*********************************************************************************************************/ -->
<!-- /***************************************** Background Information ****************************************/ -->
<!-- /*********************************************************************************************************/ -->
{{:Templateimpl:bg | initials=MD | title=scanserial | desc=Using scanserial to find your serial ports. | project=OE 5.0 }}

Linux systems use virtual files to provide device nodes which represent hardware devices attached to a system.  These device nodes reside in the <code>/dev</code> directory.  Each device node corresponds to one device, or to one endpoint within a device.

The serial ports typically are represented by device nodes with one of the two following naming schemes:

;Standard Serial Devices
: <code>/dev/ttyS</code>*
;USB Serial Devices
: <code>/dev/ttyUSB</code>*

Any given system may have one or both of these types of serial devices attached to it.  Serial ports provided by a motherboard or add-in PCI/PCIe card are classified in this document as Standard Serial Devices.  USB to serial devices, including USB devices which provide several serial ports, are classified in this document as USB Serial Devices.

Serial devices normally provide a character device (rather than a block or FIFO).  Each device node describes the type of device it is associated with, in this case character, and has an associated major and minor magic number.  The magic numbers are used to identify to the operating system kernel the specific device on the system to which the device node corresponds.  Further details about device nodes are beyond the scope of this document, but can be found on this site and elsewhere in documentation on Linux device drivers.

<!-- /*********************************************************************************************************/ -->
<!-- /*****************************************  General Information  *****************************************/ -->
<!-- /*********************************************************************************************************/ -->
{{:Templateimpl:geninfo | initials=MD | title=scanserial | desc=Using scanserial to find your serial ports. | project=OE 5.0 }}

The <code>scanserial</code> tool is provided by EMAC to assist customers in getting a development environment set up.  Since <code>scanserial</code> is an EMAC provided tool, you will need to install it unless you are using an EMAC LDC (which has it pre-installed).

If your Ubuntu machine isn't already configured to use the EMAC apt repository for installing software, you will need to [[Getting_Started_with_the_EMAC_OE_SDK| follow this guide]] on how to do so.  When your system is configured for the EMAC apt repository, you can install the <code>scanserial</code> tool by installing the <code>emac-tools-util</code> package.  To install it with <code>apt-get</code> on the command line, run:

{{cli|username=developer|hostname=developerpc|sudo apt-get install emac-tools-util}}

Alternatively, you may open the Ubuntu Software Center and search for the <code>emac-tools-util</code> project.  Clicking on the search result will provide you with an option to install the package.  Click the <b>Install</b> button to install it.

<!-- /*********************************************************************************************************/ -->
<!-- /*****************************************  Using/Working With  ******************************************/ -->
<!-- /*********************************************************************************************************/ -->
{{:Templateimpl:using | initials=MD | title=scanserial | desc=Using scanserial to find your serial ports. | project=OE 5.0 }}

The <code>scanserial</code> utility has a few options which allow you to customize the behavior of <code>scanserial</code> or find out more about it.  The list below describes these options.

;-v, --verbose
: Display verbose output.  When displaying a list of devices, this will show metadata associated with each device node.

;-c, --color
: Displays output in color (if available).

;-f, --find-loopback
: Uses the same algorithm which is used to find a list of serial port device nodes, then scans the list of device nodes for loopback devices.  Displays every  device it finds which appears to have a loopback attached.  Note that this can be fooled by connected devices which echo input back to the port, such as a logged in console on a board.

;-h, --help
: Displays help for using the scanserial tool.

;-l, --list-serials
: Lists the serial device nodes found in /dev which appear to be serial ports.  If combined with the verbose option, this will also show metadata about each one.  Add the color switch to colorize the output to make it easier to read.

;--version
: Displays the version number of the scanserial tool.

====Return Value====

The return value of <code>scanserial</code> corresponds to the success of its operation.  If the operation succeeded, it returns zero, as is the customary behavior for all *nix software.  If it fails, it will return a value greater than zero (which is also the standard behavior for software on Linux systems).

<!-- /*********************************************************************************************************/ -->
<!-- /*****************************************       Examples        *****************************************/ -->
<!-- /*********************************************************************************************************/ -->
{{:Templateimpl:examples | initials=MD | title=scanserial | desc=Using scanserial to find your serial ports. | project=OE 5.0 }}

====Listing Available Serial Ports====

Use the <code>-l</code> (lowercase L) option to list available serial ports.  Here, there are 6 standard serial ports and 8 USB serial ports available.

{{clop}}
{{cliop|username=developer|hostname=developerpc|scanserial -l}}
/dev/ttyS0
/dev/ttyS1
/dev/ttyS4
/dev/ttyS5
/dev/ttyS6
/dev/ttyS7
/dev/ttyUSB0
/dev/ttyUSB1
/dev/ttyUSB2
/dev/ttyUSB3
/dev/ttyUSB4
/dev/ttyUSB5
/dev/ttyUSB6
/dev/ttyUSB7
{{cliop | username=developer | hostname=developerpc |}}
{{closp}}

<br />

====Listing Detailed Information About Serial Ports====

The verbose option, <code>--verbose</code> or <code>-v</code>, causes <code>scanserial</code> to output much more detailed information.

{{clop}}
{{cliop | username=developer | hostname=developerpc |scanserial -lv }}
/dev/ttyS0:
	type:       	4   	line:      	 	0
	port:       	1016   	irq:       	 	4
	flags:      	0x10000040
	xmit_fifo_sz: 	16	custom_divisor: 	0
	baud_base:     	115200
	close_delay:   	50	closing_wait:      	3000

/dev/ttyS1:
	type:       	4   	line:      	 	1
	port:       	760   	irq:       	 	3
	flags:      	0x10000040
	xmit_fifo_sz: 	16	custom_divisor: 	0
	baud_base:     	115200
	close_delay:   	50	closing_wait:      	3000
{{cliop | username=developer | hostname=developerpc |}}
{{closp}}

''Further output, in this example, was truncated for the sake of brevity.''

====Finding an Attached Loopback====

When you need to figure out which device node corresponds to the specific one you wish to use, which can be especially difficult when you have a lot of serial ports (like the 14 on the system shown above), a loopback is very useful.  A loopback is a connection between the Rx and Tx lines on a serial port.  Many large vendors sell RS-232 serial loopback dongles.  In a pinch, you can make your own loopback by connecting the Rx and Tx lines together with a wire or jumper.

Once you have a loopback connected to the desired port, run the <code>scanserial</code> command with the <code>--find-loopback</code> or <code>-f</code> (the shortened abbreviated version) argument:

{{clop}}
{{cliop | username=developer | hostname=developerpc |scanserial -f}}
/dev/ttyUSB6	:	Found!
{{cliop | username=developer | hostname=developerpc |}}
{{closp}}

If you have multiple loopbacks attached, they will all show up in the output list.  If you wish to ensure that <code>scanserial</code> is checking every device node you're expecting it to check, you can add the verbose flag (<code>--verbose</code> or <code>-v</code> for short) when you call <code>scanserial</code>.  For example, if you have two loopbacks attached and call <code>scanserial</code> with the verbose flag set, it might look like this:

{{clop}}
{{cliop | username=developer | hostname=developerpc |scanserial -fv }}
/dev/ttyS0	:	no
/dev/ttyS1	:	no
/dev/ttyS4	:	no
/dev/ttyS5	:	no
/dev/ttyS6	:	no
/dev/ttyS7	:	no
/dev/ttyUSB0	:	no
/dev/ttyUSB1	:	no
/dev/ttyUSB2	:	Found!
/dev/ttyUSB3	:	no
/dev/ttyUSB4	:	no
/dev/ttyUSB5	:	no
/dev/ttyUSB6	:	Found!
/dev/ttyUSB7	:	no
{{cliop | username=developer | hostname=developerpc | }}
{{closp}}


<!-- /*********************************************************************************************************/ -->
<!-- /******************************************     Conclusion      ******************************************/ -->
<!-- /*********************************************************************************************************/ -->
{{:Templateimpl:conclusion | initials=MD | title=scanserial | desc=Using scanserial to find your serial ports. | project=OE 5.0 }}

The <code>scanserial</code> tool greatly simplifies the once cumbersome, manual, trial-and-error process of figuring out which of the potentially 100+ device nodes have associated physical serial ports, and which of those is/are the one(s) you're looking for.  This freely available tool can save you a great deal of time when configuring serial ports.  If you don't need to do perform this task right now, perhaps because you're using an EMAC LDC, you would still be wise to remember that this tool exists so that you will be able to find it later.


<!-- /*********************************************************************************************************/ -->
<!-- /******************************************   More Information   *****************************************/ -->
<!-- /*********************************************************************************************************/ -->
{{:Templateimpl:moreinfo | initials=MD | title=scanserial | desc=Using scanserial to find your serial ports. | project=OE 5.0 }}
* [[Serial_Connections | Making Serial Connections to EMAC OE Linux 5.x Machines]]
* [[System_Log_In | Logging Into an EMAC OE Linux 5.x Machine]]
* [[Network_Connections | Connecting an EMAC OE Linux 5.x Machine to a Network]]


{{:Templateimpl:whatnext | initials=MD | title=scanserial | desc=Using scanserial to find your serial ports. | project=OE 5.0 }}
* [[Quick_Reference | EMAC Quick Reference]]
* [[Network_Configuration | Configuring Networking]]