Measurement Computing Personal488 rev.3.0 - Manual (Page 146)

C-8 Troubleshooting 03/16/01 Personal488 for Windows 95/98/Me/NT/2000
My program has been running on an older PC for many years without any problems. Now I have installed
Personal488 on my new PC and verified that the installation is working correctly. When I run my program it
stops and reports the message “Time out on data read.” Why?
With today’s fast PC, timing problems often occur when an application migrates from a slow PC to a fast PC.
This is due to programmers sprinkling delays throughout their code in order to wait for instruments to perform
tasks. Some programs, originally written on slow PCs, did not use delays because code execution was slow. Some
programmers even used For..Next loops as delays. All of these scenarios become problems when faster PCs are
used. For example, inherent delays in slow code disappear; For..Next loop delays become shorter; And programs
stop running. These issues can be avoided by polling instruments for status before sending or receiving data. If
time delays must be used then make sure the delay reads the system clock for timing information.
I am programming in Visual Basic. My interface is installed correctly, but the “Enter” function returns
immediately with no data. Why?
The most common trap Visual Basic programmers fall into is not allocating space in a string variable.
Dimensioning the string variable is not enough. Adequate space must be allocated in the string for the expected
data. For example, MyString = Space$(10) allocates enough space for 10 characters in MyString.