Siemens 3964R User Manual page 35

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3. If (1. and 2.) above do not work, verify the value of the ComBoostTime parameter
in your . file. This parameter represents the number of milliseconds that
SYSTEM INI
a virtual machine can process a COM interrupt. (The default value is 2.) We do not
recommend that you normally change this setting however, if you are receiving
errors such as "Receive Overruns" or "WCRE=-2", try increasing the value to 20.
Verify the parameters for WWCOMTSR.
Do not specify a receive and/or transmit buffer size of 8!
For example:
Correct:
COM1:0 COM2:1,2048,2048
COM1:0 COM2:1
Incorrect:
COM1:0 COM2:1,8,8
Does your computer crash when you try to communicate through the COM port?
If so, verify that each TSR has a unique software interrupt.
There is a utility, ShowSoft, available on the Knowledge Base CD that can assist
you in determining the software interrupts that are available.
Does your computer lock up?
Verify the COM port's IRQs do not conflict with each other or with any other
communication boards in the computer.
If the PLC or field device has more than one COM port, verify that you are
connected to the correct port.
The COM port on your computer uses the RS-232 hardware communication standard.
Meaning, you must connect the cable from the COM port to an RS-232 compliant
device.
Note A common mistake is to connect to an RS-422 or RS-485 port on the PLC. To do
this, you need an RS-232 to RS-422/485 conversion device.
If possible, use an external converter instead of a board-based converter that plugs into
a slot in the computer. A board-based converter is typically more difficult to get
working for inexperienced users. If a board-based converter is not set up properly, it
can conflict with other communication boards in the computer such as, internal
modems.
If you are using the Windows 95 operating system, verify the following:
4. Click Start on the Windows Taskbar. Point to Settings, then click Control Panel in
the menu. The Control Panel dialog box will appear.
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