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mode (The ECP mode is the Enhanced Capabilities Port mode and is the “Cadillac” mode) or
it just doesn’t work perfectly like it should.
We recommend using the new USB2EPP cable for best performance via USB-2 ports.
Otherwise a second parallel port should be installed for the EPP2000 spectrometer(s). These
are the EPP-PCI for desktops or EPP-PCMCIA for notebooks. This ensures 2 things: 1) the
spectrometers will always work immediately with this low cost adapter card and no time will be
wasted on installation and testing. 2) You will be able to printout the spectra at almost at the
same instant that you display it using the systems LPT1 printer.
When you are using a notebook computer with the EPP2000 spectrometer, it is possible to
connect the instrument directly to the printer port. For some notebooks this may not work,
however an alternative exists to provide the desired result. A PCMCIA adapter is available to
provide a second printer port that is EPP capable and compatible with the EPP2000
spectrometer(s).
The EPP architecture and signaling protocols provide a mechanism for a fully interlocked data
transfer within a single CPU I/O cycle. What this means is that when an I/O instruction is
executed, the port hardware will synchronize with the external peripheral (EPP2000
spectrometer) and automatically generate the necessary handshake signals to transfer data to the
peripheral or receive data from the peripheral. This provides transfer data rates to over 2M
bytes per second. This translates to over 1 million wavelengths per second !
EPP2000 Connector Interface Signals
The DB25 connector contains standard parallel port signals plus a few that have been defined in
EPP mode for the EPP2000 spectrometer, which is allowed by the IEEE1284 specification.
The SPP signals identified in the table below show the Standard Parallel Port signals as
originally defined on the IBM PC 25 pin printer connector. The I/O (input/output) column
below is from the computer’s point of view, with exception to the user-defined signals. All
signal are 0 to 5 volts DC (TTL).
Pin SPP Signal EPP Signal I/O EPP Signal Description______________________
1 nSTROBE nWRITE O Active low, indicates a write operation, high on read
14 nAUTOFEED nDATASTB O Active low, indicates Data read/write operation
17 nSELECTIN NADDRSTB O Active low, indicates Address read/write operation
16 nINIT nRESET O Active low, peripheral reset command.
10 nACK nINTR I Peripheral interrupt to the host computer.
11 BUSY nWAIT I Handshake. When low OK to start a strobe cycle.
12 PE user defined O Low to High indicates start of spectral scan (TTL)
13 SELECT user defined I Spectrometer auxiliary power bus +5Volt input
15 nERROR user defined I External trigger, hold low to disable (TTL)
2-9 Data 0-7 Address 0-7 BI Bi-directional Address/Data lines.
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