Using Logic Analyzer Inputs with the VSA

Using the Logic Analyzer with the 89600 VSA involves the following steps:

• Connect to the Logic Analyzer
• Start and link the Logic Analyzer and VSA applications
• Configure and start the digital measurement
• Define Triggering

Connect to the Logic Analyzer

Use the VSA Instrument Manager to connect the Logic Analyzer to the 89600 VSA.

The Instrument Manager requires either the dotted IP Internet Protocol: A set of instructions defining how information is handled as it travels between systems across the Internet. address (e.g., 192.168.0.101) or the host name of the Logic Analyzer. To use the Logic Analyzer application residing on the same PC as the VSA, use the name localhost.

An added Logic Analyzer entry will cause a Logic Analyzer selection to appear in the Possible Logical Instruments on the VSA New Hardware Configuration dialog box (Utilities > Hardware > Configurations > Add button) at startup or after the Rediscover Instruments button is clicked.

Start and link the Logic Analyzer and VSA applications

When the VSA application is started, it automatically links to the last hardware setup used. If this was not a Logic Analyzer, click Utilities > Hardware > Configurations. Select the Analyzer Configuration that contains the Logic Analyzer. The VSA will then link to the Logic Analyzer application running at the IP address or host name shown.

If the Logic Analyzer application is not running, it is automatically started. A Panel Lock message window appears on the Logic Analyzer window showing that the Logic Analyzer has been locked by the VSA.

If Logic Analyzer settings need to be changed, click Cancel on the Panel Lock message window or on the VSA, click Control > Disconnect. The Panel Lock message window on the Logic Analyzer window goes away and changes the Logic Analyzer setup. When the Logic Analyzer settings have be changed, go back to the VSA window and click Control > Restart or click the Start icon. This will link the Logic Analyzer to the VSA and bring up the Panel Lock message window on the Logic Analyzer window. Now resume setting up or running the VSA measurement.

Logic Analyzer link examples

• LA and VSA Running on the Same PC
• LA and VSA Running on the LA Mainframe
• LA Running on LA Mainframe, VSA Running on PC

Configure the Digital Data Measurement

Open the VSA Input Properties, click Input > Digital. The Digital Input Properties dialog box is where the properties for the digital measurement are set up. For information about Digital input properties, see About Digital Input Properties.

Specify the input data sample rate and center frequency

Specify the data Sample Rate (Input > Digital > Frequency Sample Rate parameter), note that the data sample rate can be different from the digital bus clock rate. Specify the center frequency (Input > Digital > Frequency Center parameter) for proper frequency axis scaling.

Specify the Data Sign

Specify the proper digital data sign convention (two's complement or offset binary), select from the Data Sign drop-down list.

Specify the Digital Data Composition

Only data from a single module can be analyzed at a time. Select the measurement data source from the Composition Module Name drop-down list.

The input data can be composed of real or complex data parts. Real data is only composed of 1 data part and uses a single bus. Complex data can be expressed as I/Q pairs (or magnitude/phase) with each data part using a separate bus or both parts interleaved using a single bus. Use the Composition Parts drop down to select the data part mapping.

Multi-Channel Measurements

For multiple channel measurements, the digital data setup configuration, including the Sample rate, Center Frequency, and Module Name parameters, is applied to all channels and the Channel drop-down list setting is ignored (Input > Digital). However, separate channels can use different software Tools and Bus Names. Use the Channel drop-down list to specify which input channel the channel independent parameters are applied to. See the following table:

Parameter	Applied to All Channels	Independent Channel Assignment
Freq-Sample Rate	Y	-
Freq – Center	Y	-
Comp - Module Name	Y	-
Comp - Tool Name	-	Y
Comp - Parts	Y	-
Comp – Bus Name 1	-	Y
Comp – Bus Name 1	-	Y
Data - Sign	-	Y
Data – Scale I	-	Y
Data Scale Q	-	Y

A different software Tool (e.g., a signal extractor) can be optionally specified as the data source for each input channel independently. To specify a Tool, first select the desired input data channel (Channel drop-down list) and then select the Tool Name (Tool Name drop-down list), repeat for each input channel. Select the -none- Tool Name (default) when data is to be analyzed directly from the hardware module. The Tool Name drop-down list only shows the Tools connected to the previously selected data module.

The VSA supports analysis for data signals composed of two data parts. The VSA provides two Bus Name drop-down properties for data signals composed of two data parts (I and Q or Magnitude and Phase). Each Bus Name drop down list contains the available Bus Names for the specified Data Module or Tool (The Bus Names are defined in the Logic Analyzer application). Use the Bus Name drop-down list to specify the bus, or buses, for measurement analysis.

Custom Input Channel Configurations: When using the Input Channel Configuration dialog to specify or modify the input channel configuration mapping, only the VSA default set of channel configuration mappings are allowed; "invalid" channel configuration mappings are disallowed and the "OK" button is disabled "greyed out".

Logic Analyzer Configuration Changes

If the Logic Analyzer configuration needs to be modified, first disconnect the Logic Analyzer from the VSA measurement, click Control > Disconnect. Then go to the Logic Analyzer application and make the changes. The Logic Analyzer changes can include adding buses or changing bus names. Back in the VSA, click Refresh Names on the Digital tab of the Input Properties dialog. This will update all the Module, Tool, and Bus Name properties.

Start the Measurement

At this point start a measurement and see the results. The VSA is designed to be interactive, showing the result of any change made in real time. This corrects setup problems.

When a change is made to the input to the Logic Analyzer, the change is not seen in the 89600 VSA until the VSA runs to the end of the current Logic Analyzer data buffer and instructs the Logic Analyzer to run again. Force the Logic analyzer to run again immediately by clicking Control > Restart or clicking the Restart button on the VSA.

Force the 89600 VSA to run the Logic Analyzer for every scan by choosing Block mode rather than Continuous. In the 89600 VSA, click Input > Extensions. In the Extensions dialog box, select Block for the Data Mode parameter.

If someone has previously set up and run a logic analyzer measurement and has saved a configuration file (with data), this data can be analyzed with the VSA. Previously saved data can be analyzed by using the Logic Analyzer application in offline mode. The Logic Analyzer software can be installed on the host PC and doesn't need to be connected to measurement hardware. Start the Logic Analyzer application and recall the Logic Analyzer configuration (with data) file. The file contains recorded data for all channels, even if they weren't assigned to data buses when the setup was saved. Change or add bus/signal descriptions and view them on the Logic Analyzer. Once the Logic Analyzer is configured, start the VSA, link to the Logic Analyzer application and analyze the data. In offline analysis, when the VSA gets to the end of the Logic Analyzer data buffer, it returns to the beginning and continues the measurement.

Define Triggering

Click Input > Trigger on the VSA and select either free run or external as the trigger style.

When the 89600 VSA trigger style is Free Run, it ignores any trigger setup on the Logic Analyzer. The VSA will process the input data as quickly as possible, without waiting for any kind of triggering signal.

When the 89600 VSA trigger style is External, the VSA associates time 0 with the Logic Analyzer sample 0. The VSA will set a pre- or post-trigger delay in the VSA Input Properties Trigger Tab dialog box.

The following formulas can be used to approximate maximum pre- or post-trigger delay values:

Maximum Post Trigger Delay =	/sample rate
Maximum Pre Trigger Delay  =	((Acq Depth)(1-%poststore/100)-block size))/sample rate

See Also

Logic Analyzer Software Setup