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COM Port Element

COM Port Element provides bidirectional data exchange through the serial port (COM) on a PC computer. The element can be used for sending digital codes that are synchronized with events in your experiment. Also, the serial port element can be used for asynchronous data transfers to the external devices.

Table of Contents [Hide/Show] Summary Properties Description Snapshots Practical Use     Manual (output)     Output on event Onset     Triggering on specific Input     Manual Input Listening     Testing the serial port element Notes

Description ¶

COM port is an element that provides bidirectional data exchange through the serial computer ports: COM ports and USB ports (with special drivers). Using the COM port element is very easy: you simply chose one of the existing serial ports on a computer, set up a few port settings and select the element working mode. The element supports four working modes that cover most of the typical usage scenarios in experiments.

Snapshots ¶

Practical Use ¶

Manual (output) ¶

In this mode the serial port element can be used for sending data through the serial port at any chosen moment of time. You have to control this process manually in your code snippets in two steps. First, you should settle some data in an output buffer by assigning a string value to the [Output Buffer] property of the element. Then, the output buffer can be sent to the port immediately after you set the [Send now] property of the element to true (initiating the runtime action). You can perform these steps multiple times while your experiment is running (it not necessary to have the parent event active in this working mode).

Output on event Onset ¶

In this mode the serial port element can be used for sending data through the serial port synchronously with activation of the parent event. Before the activation or in the design time you should settle data in an output buffer by a string value to the [Output Buffer] property of the element. Immediately after activation of the parent event the output buffer will be sent automatically through the serial port. The output buffer can be changed at the runtime at any time but each new sending will require reactivation of the parent event.

Triggering on specific Input ¶

In this working mode the serial port element monitors all input coming through the serial port in order to detect a moment when the specific string value, the trigger string, arrives. The sought value is defined by the [Trigger String] property of the element. The serial port element signals the arrival moment by switching to the triggered state. Such triggering is always accompanied with recording of the exact trigger time and executing of the dedicated code snippet (if present). Thus, you can use the specific port input for controlling a flow of your experiment, performing custom actions and collecting accurate input timing. Notice that the element in this working mode has an action scope. This means the input monitoring and element triggering are possible only while the parent event is active.

You can share the same port input among several serial port elements with each element seeking for its own trigger string. The elements also can be set to have multiple triggering in case in the port input may contains multiple occurrences of the trigger string (by default, in this working mode the element is triggered only once on the first trigger string arrival).

Manual Input Listening ¶

In this working mode the serial port element simply collects all port input coming through the serial port while the parent event is active. The coming input is placed into the input buffer which can be accessed at runtime by reading the [Input Buffer] property of the element in code snippets. The input buffer is designed to be forcibly refreshed on every Running Cycle of the parent event. If you want to avoid data losses, you should take into account the expected input intensity and provide continuous reading of the input buffer. The best strategy is to read the input buffer in the OnRunning snippet of the parent event (a fresh data is guaranteed) and set the size of the input buffer to be always sufficient to store all input coming between two Running cycles.

Testing the serial port element ¶

You can test a work of the serial port element with its current settings at designtime by initiating either of two design-time actions: [Test Output] and [Test Input]. EventIDE will try to simulate element's runtime behavior for a short time, while it can be checked with an external hardware or software. [TestOutput] action initiates a single transfer of the current output buffer through the port. [TestInput] action calls a text window that, while open, shows the coming port input.

Notes ¶

1. For better synchronization of output transfers (in AutoOutput mode), move the Serial Port element at the top of the elements list in the parent event. The elements in the list are activated one by one, as soon as the parent event is activated, so the top position in the list decreases possible time delays.
2. The serial port element always operates with input and output port data in the string format, performing string-binary conversion automatically. For the desired adequacy of this conversion the appropriate encoding has to be selected in the element port settings.
3. You can use multiple serial port elements that share the same serial port. However, in this case you should take in account possible performance issues, which are likely, for example, in cases of the intensive port input.
   
   

	Name	Size
	COM-Port-Element-Icon.png	3.19 KB
	SerialPort.png	575.29 KB
	SerialPort_sm.jpg	58.98 KB