Generic Serial Device

This page was written by Pluto and imported with their permission when LinuxMCE branched off in February, 2007. In general any information should apply to LinuxMCE. However, this page should be edited to reflect changes to LinuxMCE and remove old references to Pluto.

Generic_Serial_Device (also knowk as GSD) is a Pluto device that allows enduser to do simple programming for RS232, serial USB or network connected devices.

Note : The information is not quite complete because I'm not the original author.

Short description

It's a standard DCE device, it only can execute commands and send events (no event handler yet, but Aaron wants it badly).

The main idea is instead of programming a device in C++, compile, link whith proper libraries you can edit (in a webpage) few lines of code in ruby which will be executed when device receives that command. It exports several objects into ruby so you'll have access to devicedata, device hierarchy, established connection and so on.

The ruby code for each device template is storred somewhere in InfraredGroup_Command table. To edit the code go to Wizard> Devices > Generic_Serial_Devices on pluto-admin website. You have to add a device from a device template in order to see anything in that page.

Select the device, and click "RubyCodes" button to be able to edit code that will be executed. You should be able to see commands that are specified in device template (like ON/OFF/WhateverElse) and a group of Internal Commands which are used to perform certain actions ar to add helper functions.

If the command you are trying to add doesn't show on first page, go to Add/Remove commands and add more commands for your device.

Ruby source code

There are 2 forms of ruby code you can write :

• standard ruby code (check [1] and [2] for syntax, referencies and programming guides)
• short form for conn_.Send

<$"PWON\r"$>

which simply will send the string "PWON\r" to device.

You'll have to quickreload router to get new code. Restarting GSD only will keep old code because the code is supplied by Infrared_Plugin which caches pluto_main and won't update it's cache without full restart of DCERouter. With this code it creates a ruby source which will be interpretted by embedded ruby.

It will create methods called "cmd_CmdIDx" for each command(x) defined in web interface except Private_Method_Listing which will be inserted in the body of the class directly without wrapping.

The source usually looks like (DevID is iPK_Device of specific device, CmdIDx is iPK_Command ) :

require 'Ruby_Generic_Serial_Device'
class Command < Ruby_Generic_Serial_Device::RubyCommandWrapper
end
class Device_DevID < Ruby_Generic_Serial_Device::RubySerialWrapper
def cmd_CmdID1(paramlist)
    @returnParamArray.clear
    ### WEB CODE for CmdID1 GOES HERE ###
    return @returnParamArray
end
def cmd_CmdID2(paramlist)
    @returnParamArray.clear
    ### WEB CODE for CmdID2 GOES HERE ###
    return @returnParamArray
end
...
def cmd_ReceiveCommandForChild(cmd)
    ### Process_Receive Command_For_Child GOES HERE ###
end
...
### Private_Method_Listing GOES HERE ###
...
def initialize()
    super
    @returnParamArray=Array.new
end
### Generated Setters/Getters goes here (may be empty, but usually looks like below) ###
def data_set(value)
    @returnParamArray[19]=value
end

end

There might be more then one class definition in that source. This may happend when child device is itself a GSD device.

Command details

When the command from DCE arrives it is routed to specific device and cmd_XXX is runned. The commands are runned one by one, meaning thet you can not run 2 commands simultaniosly. This limitation is implied by embedded ruby interpretor which fails if runned from multiple threads. DCE commands may have return parameters (well known GetVideoFrame), as ruby can return only 1 parameter the @returnParamArray was added. You can see that in each method we insert @returnParamArray.clear then the real code and then return @returnParamArray. Also some setters are generated (like the one from above) for code readability.

Beside usual DCE command you'll see some Internal Commands. Here goes a small list and what they do:

• Private Method Listing - used to insert all kind of helpers
• Process IDLE - method executed once in a while (may be used to keep connection alive, scan for new devices on serial bus)
• Process Incoming Data - called when some data is available
• Process Receive Command For Child - called if the device has children and those are pretty dummy (like Lights under CM11), so practically the parent will do the job. As a parameter you have cmd which is a wrapper for DCEMessage, so you'll have access to deviceId, senderId, commandID and so on.
• Process Initialize - called when device is starting (to perform handshake with device or some other initialisation required by protocol)
• Process Release - to close gracefully connection with device (say "good bye" or something)

Implementation notes

There are several classes that actually needs to be touched. Most of the other classes are just for wrapping DCE objects (like Device, Message, Connection and so on) and exporting them into ruby.

Examples

For more details check GSD_Ruby_Interface

  0:require 'Ruby_Generic_Serial_Device'
  1:class Command < Ruby_Generic_Serial_Device::RubyCommandWrapper
  2:end
  3:class Device_47 < Ruby_Generic_Serial_Device::RubySerialWrapper
  4:#### 84 ####################################################################
  5:def cmd_84(data, format, disable_aspect_lock, streamid, width, height)
  6:@returnParamArray.clear
  7:conn_.Reconnect()
  8:auth_s=device_.devdata_[114]+":"+device_.devdata_[115]
  9:auth_a=Array.new;
 10:auth_s.each{|c| auth_a.push(c)}
 11:
 12:fix_path=device_.devdata_[2];
 13:fix_path='/'+fix_path if(fix_path[0]!='/'[0]);
 14:
 15:s = "GET "+fix_path+" HTTP/1.0\r\n"
 16:s+= "Accept: */*\r\n"
 17:s+= "Authorization: Basic "+auth_a.pack("m").chop+"\r\n"
 18:s+= "\r\n"
 19:
 20:conn_.Send(s)
 21:recv=""
 22:while(true)
 23:  buff=conn_.Recv(16384, 5000)
 24:  if(buff.length() == 0)
 25:     break
 26:   end
 27:   recv = recv +  buff
 28:end
 29:if (recv=~ /^HTTP[^\r\n]+200\sOK.+?\r\n\r\n(.+)$/m)
 30:  fileName="/tmp/ip_camera_img"+device_.devid_.to_s
 31:  data_set($1)
 32:  format_set('jpg')
 33:end
 34:return @returnParamArray
 35:end
...
194:#### START SETTERS ####################################################################
195:def initialize()
196:super
197:@returnParamArray=Array.new
198:end
199:def data_set(value)
200:@returnParamArray[19]=value
201:end
202:def format_set(value)
203:@returnParamArray[20]=value
204:end
205:####  END  SETTERS ####################################################################
206:end