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Workbench PC for DOS and Quicklog for DOS: Using the Serial Icon to Communicate With an RS-232 or RS-422 Device

The following application note is intended to aid a first time user of the Serial icon in QuickLog or WorkBench PC (DOS). In order for the Serial icon to operate correctly there are certain software and hardware guidelines that must be followed. Please check the following list to ensure that you are properly set up to use this icon:

  1. Check that the port is working correctly by changing the mouse over to that COM port. Typing mouse/n before loading WorkBench or QuickLog will force the mouse to Com port n.

  2. Use "run" in the serial icon to test your commands. It may be necessary to click on "run" rapidly for a while to get the command to engage.

  3. Having the mouse active on the screen can cause problems. If the mouse is moving during data acquisition it can interfere with the serial communication and cause points to be missed. Disable the mouse with Ctrl-Alt-8.

  4. Make sure that the correct modem cable is being used. There are two types of end connection, DTE and DCE. If both the computer and the external serial device have the same connection a null modem must be used. PC's are usually DTE.

  5. Continuous mode can lead to missed characters in the input data. This is due to the one character input buffer. If some characters have already been sent when the serial icon accesses the line then those characters are missed. This can be overcome, to a degree, by using two input commands, one after the other. In this way a whole line of data is read, although the first line is still lost.

  6. Make sure that the user knows that there is a serial configuration in the menu that needs to be set up to perform serial communication.

  7. The pause command waits for a specified time in milliseconds. It is important to note that after the pause is set the serial icon is exited and the rest of the worksheet runs. Therefore, if a serial icon is set to be accessed by WB once every five seconds, and the pause is set to a few milliseconds, the total pause will be 5 seconds plus the pause time. To overcome this, insert a five second pause into the serial command structure.

Before a user tries to get a complex set of commands running they should first try to output or input something simple. This will ensure that the serial setup is correct and that all connections are made.





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