Measurement Computing WaveBook rev.5.3 - Manual (Page 128)

7-20 Troubleshooting 979194 WaveBook User’s Manual - IO version
(5) Topic: ECP and EPP
Question: My computer uses ECP. Is ECP the same as EPP?
Answer: No; ECP (Enhanced Capabilities Port) is a different protocol than EPP (Enhanced Parallel Port).
If the WaveBook fails to communicate in ECP mode, make certain that the WaveBook
hardware is actually capable of ECP communications. This can be done as follows:
1. Locate the LPT port communications chip on the main board, near the connector that the
parallel cable connects to. The chip is relatively large and is stamped “262-0301,”
or “262-0301, rev B.” A 262-0301 rev. B" chip supports ECP, the earlier rev does not.
Contact the factory in regard to upgrading. Note that most units purchased before July
2000 do not have ECP support .
2. Verify the parallel port hardware is in ECP mode. For ports built into the computer’s
motherboard, the port is usually configured using the computer’s BIOS setup utility
(accessible during computer start up). See your computer's specific documentation
regarding accessing the BIOS setup utility and configuring peripherals.
3. Verify the parallel port is configured [in the Windows Control Panel] as an "ECP parallel
port" and not "Parallel port."
(6) Topic: Sampling Rates
Question: Does the WaveBook really collect data at 1 MHz and what should I expect on my PC?
Answer: Yes, the WaveBook samples at 1 MHz. But your computer may not. The PC’s performance is a
function of the hardware configuration, operating system, background task, and other factors.
The PC could very well be a bottleneck in regard to sampling.
Question: What transfer speeds can I expect from a standard 8-bit parallel port?
Answer: A typical computer will achieve 80K to 90K samples/sec [through-put to the PC].
Question: I realize that the WBK20A and WBK21 are interface options. Will they improve my speeds?
Answer: In the majority of cases, by far, both products result in higher through-put [than you would see
with the use of the standard 8 bit port. The exact amount varies with PC configuration.
When using the WBK21, ISA plug-in board, 1 MHz through put is more the rule than the
exception. Because this boards sits directly on the bus, most computers can handle the data rate.
The WBK20A (PCMCIA card) plugs into the PC-card slot on the side of the notebook PC. Up
until early 1997, all notebooks with these slots were PCMCIA type. In these older computers,
1 MHz was often seen, but 750-800 kHz was typical. In early 1997 notebooks started shipping
with a PC card bus instead of the PCMCIA card slot. This change was almost completely
transparent to PC users since the PCMCIA card plugs in and the PC Card bus is backward
compatible with PCMCIA cards. However, one important change occurred. The WBK20A
appears to operate slower in the new PC Card slot. With this change, 1 MHz transfer rates using
the WBK20A in a PC Card slot are almost non-existent, instead, 300K to 500K samples/sec is
typical.
Question: I'm using the WBK20A but because of my PC architecture, the system is still slower than I
require. What else can I do?
Answer: One option is to install a WBK30 memory card. This increases the FIFO buffer inside the
WaveBook. While this option does not increase transfer speeds, it does extend the length of
time an acquisition can run before a buffer over flow occurs. The exact duration is a function of
sampling rates and transfer speeds. For example, assume you are using a WaveBook/512 in
packed mode with the WBK30/128. This option holds 128 Mbytes (64 Msamples) of data.
Furthermore, let us say you are digitizing at 1 MHz and transferring data at 400 Ksample/sec
via a WBK20A. In this case, you could expect to acquire data for about 1 minutes and 51
seconds. In that amount of time, you would have collected about 148.7 Msamples. This is over
a quarter gigabyte of data.