Device Channel Tracing

 

• InSight has the ability to monitor POS terminal device I/O at two different levels.  The first level is at the interface between the application and the device-specific driver.  The 2 ^ndlevel is between the device-specific driver and the general purpose device channel bus driver.  Being able to trace at the device channel level allows possible additional data to be seen.  Specifically, it allows capturing data that is added or removed by the device-specific driver.
• The 4610 printer is a good example of a device where the printer driver modifies the data flow substantially.
• Device channel tracing is not available for all devices – it is available for printers and serial ports.
• Printer device channel history is monitored and kept by default.
• Serial port device channel history is monitored and kept only if serial port monitoring is activated.
• The default device channel history buffer sizes can be modified by CDI option.
• Additional device channel tracing detail is available with a ‘low level’ device channel option.  This option enables additional protocol details to be seen such as I-frame retries for 485 devices.
• A utility program, DevChan, is provided and supports real-time collection of device channel trace data.  It supports active collection of device channel data from either serial devices or printers or both.  It also supports requesting the terminal to snapshot dump.  Both a .286 version and .exe version are available.  Source code for the program is also provided -> DevChan is one of the sample programs in the InSight SDK.
• The dump formatter supports extracting and formatting device channel trace information from snapshot terminal dumps and full terminal dumps.
• For the printer, InSight allocates two device channel history buffers.  One contains both reads and writes to the printer and the other contains only reads.  The reason for the separate read buffer is that return status from the 4610 is key to understanding many printer issues and having guaranteed visibility to a minimum number of  these printer status responses was desired.
• For device channel tracing, a system-wide (i.e. global) history buffer is allocated only after a client requests real-time device channel.  This is different for device channel than it is for normal or upper level device monitoring.  For upper level device monitoring, a global history buffer is always allocated.   For clarity/refresh: monitoring events for devices go to a device-specific buffer and to a global history buffer.  Device events are mixed together, in-order, in the global history buffer
• Optional CDI keywords: tagentPrtdevChBuffSizeKB, tagentSerial[1|2|3|4]devChBuffSizeKB, tagentDevChLowLevel

• Example device channel trace output  from formatted dump data:

 

DChnW|S2|msec     826.439|11:39:26|SeqNum 28964|ID 02(xmit  )|Port 11|Addr 65|lCtrl ??|

       Command: 08=Transmit

    xmitdata 0000: 0232 392E 3130 3030 3037 3132 0323       * 29.10000712 #  *

DChnR|S2|msec     826.448|11:39:26|SeqNum 28967|ID 02(xmtACK)|Port 11|Addr 65|lCtrl n/a|

DChnR|S2|msec     826.466|11:39:26|SeqNum 28971|ID 01(recv  )|Port 11|Addr 65|lCtrl ea |

       StatusByte1: 50    StatusByte2: 46     CRC: D431

       StatusByte1: TimerOverFlow RcvBuff2NotEmpty

       StatusByte2: Initialized  RTS   DTS

    recvdata 0000: 06                                        *                *                

 

• Formatted output field descriptions:

·          lCtrl is rs485 (sdlc) link control byte.  This is only available for recv frames unless low level tracing is enabled.

·          ‘xmtAck’ is notification that the 4690 device channel driver gives back to the upper layer driver (i.e. serial driver) that says that device has acknowledged receipt of the previous xmit.

·          SeqNum – this is an InSight terminal agent sequence number.  Every event put into any InSight history buffer increments the sequence number.  

·          Timestamp info.  A running millisecond timestamp is used to timestamp all trace entries.  Periodically (for example, at buffer wrap), the terminal agent also logs a date/time event to each of the trace queues.  The date/time event contains the clock date/time as well as the current msec timer value.  The formatter logs the msec time and the most recent clock date/time for each event.  

• Feature verification steps:  

1.      Install InSight on the primary 4690 controller by running InSighti.286

2.      Reload terminal(s)

3.      Go to a 4690 command prompt and run qsa_bin:devchan.

4.      Page to the terminal you’d like to trace

5.      Press F7 to start printer device channel tracing

6.      Run transaction on a terminal

7.      When finished, press ESC.

1.      Review devchan.out file.