cialog Overview

Seed Solutions, Version 1.9

Overview

cialog (chia-log) is a program that interacts with the AEA CIA-HF complex impedance analyzer. cialog has three primary functions:

  1. Download commands to, and upload data from, the CIA-HF, graphing the data on the client area of the window. Data can be saved in a file for future recall, or exported in a standard format for use in other analysis programs. The uploaded data consists of (at most) the SWR, resistance, reactance, and impedance measured at the connector of the CIA-HF.
     
  2. Apply a reactance resolution algorithm which determines which regions of reactance data should be considered to be negative. The CIA-HF reports only positive reactance data.
     
  3. Apply a feed system transformation to the measured data which transforms the data to the load side of a transmission line connected between the CIA-HF and the device under test (DUT). These computations produce a second set of SWR, resistance, reactance, and impedance data - the values at the far end of the cable. The loss on the transmission is also computed. The original four measured values can be augmented by 5 computed value.

With version 1.08, cialog also works with the N2PK VNA. This mode of operation is described on another page.

Serial Interface

The CIA-HF is connected to the computer via a serial RS-232 COM port. A special cable is needed to connect the CIA-HF to the computer. The special end is the CIA-HF end, which uses a 1/8" stereo plug. The cable is described on the Reference page.

The COM port (COM 1 to COM 8) which is connected to the CIA-HF must be specified to cialog via the CIA->CIA COM Port Number is popup menu.

cialog does not open the COM port until it needs to communicate with the CIA-HF, due to a user-initiated command. At this point, if cialog is programmed with an incorrect COM port number, it will either be unable to open the COM port because the port hardware is not present on the computer, or, it will be able to open the port, but the communication will fail because the CIA-HF communication protocol is not available. If this is the case, double check the port number which connects to the CIA-HF, and that the same number is set in cialog. The serial line characteristics such as baud rate, are fixed by the CIA-HF. These settings are automatically used by cialog. The only setting in cialog is the COM port number.

cialog closes the COM port as soon as it is done communicating with the CIA-HF for a single user-initiated command. This behavior can lead to some issues on laptop and notebook computers.

Basic Operation

Here is a quick overview of the cialog use model.

The serial cable is connected between the computer and the CIA-HF. The CIA-HF can be powered up either by the front panel button, or through a cialog command. If you are planning on extended measurement sessions, an external power supply may make sense for the CIA-HF.

There are (at least) two ways to think about acquiring data with cialog.

In the first approach, the CIA-HF is adjusted via the front panel until the desired data and frequency span is visible on the LCD screen. When the CIA-HF is displaying the desired data, cialog can be used to capture the data. cialog uploads the frequency and sample width as well as the data

In the second approach, the cialog Custom Capture dialog is used to specify a frequency range and step size of interest. The entire data collection operation is driven from cialog.

In the first case, the CIA-HF is the center of activity, and cialog is simply used to capture data of interest. In the second case, the entire process is controlled from cialog, and the CIA-HF is not even touched.

When new data is captured, any existing data is automatically discarded, and the graph is erased before the new data is drawn. When the new data is captured, cialog will be in Single Data Set Mode, since there is a single data set loaded in the program. It is then possible to draw all of the data traces in the data set on one graph. If you want to save or export the data, it must be done before the next capture, or the graph is erased, since that second capture or erase will discard all previous data.

The File->Open Data command adds the file data set to the existing data sets loaded into cialog. If you want to view the contents of a saved file in Single Data Set Mode, be sure to erase the graph before loading the data, so that a single data set will be loaded into cialog.

Be sure to check and verify the reactance resolution and feed system settings before capturing data. The reactance resolution algorithms and feed feed system transformations are performed as the last step in data capture. If they are set incorrectly, the data capture must be redone.

The Statusbar

The statusbar is located along the bottom of the main window. It contains four regions of status information. Here is an example:

Statusbar Example
Statusbar Example

The regions, in left to right order, are:

  1. Data under cursor: When the mouse cursor is over the graph, the Frequency, SWR, Ohms, and dB Loss values under the cursor are shown. In order to find the value of a trace at some point, move the cursor over the line, then read the value from the statusbar. This is usually easier and more accurate than trying to interpret the axes labels.  If the Ctrl key is pressed when the cursor is over the graph, this region will display the complex impedance measured at the CIA-HF in polar format (degrees and angle). If the Shift key is pressed when the cursor  is over the graph, the complex impedance measured at the load (after a feed system transmission line) will be displayed in polar format. If the Ctrl and Shift keys are pressed, the region will show the standard data. In order to show the complex impedance, either at the CIA-HF or at the load, the required data (resistance and reactance) must be available in the data set. If the data is not available (it was not captured, or no feed system was used), then the standard data will be shown in the first statusbar region.
     
  2. Graph Size: The size of the graph, in pixels. This information is useful when you are trying to duplicate the size of a previous graph, so that a set of graphs have the same size.
     
  3. COM #: The COM port number which is selected on the CIA->CIA COM Port Number is popup menu. NOTE: if cialog is in VNA mode, this region will read VNA, as opposed to the COM port number, which is not used by the VNA.
     
  4. Data Folder: The name of the data folder specified on the Set Data Folder Dialog Box. This is the folder name which will be used to initialize the file save, open, and export dialogs.

 

Last update: Sunday, October 31, 2004 11:38:22 AM
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