Meilhaus Electronic ME-5100 cPCI, Manual, Page: 20 / 43

3.6 External Interrupt
If required, you can also monitor the bit-pattern of a digital input
port. The “bit-pattern change” mode is available on the ME-5100.
As soon as the specified event occurs, an interrupt is issued and
passed directly to the PC.
The digital inputs/outputs are programmed in the single operating
mode. The interrupt handling is carried out with the
func-
tions; see also chapter 4.3 on page 30.
3.7. Additional Functions
You can make the following settings for adapting to your application
regardless of the operating mode.
3.7.1 System Clock Output
If required, you can output the 66 MHz clock (L_CLK) at pin 29 of
the 78-pin D-Sub connector. A 100
Ω
resistor must be fitted at
R55 for this purpose. You can find the position of R55 with the aid
of Figs. 4 and 5 (page 16).
Note: Remember that crosstalk between the clock and the signal
lines can easily happen in the external wiring. We recommend use
of the optional ME AB-D78/IDC adapter board, where a ground line
is included between each signal line. Used together with a suitable
ribbon cable, you can minimize the crosstalk in this way.
3.7.2 Termination
For optimum signal matching, you can enable via software, an ac-
tive 110
Ω
termination at the digital inputs/outputs of each port.
The termination circuits are effectively protected against overload
by the combination of current limiting and thermal shutdown (with
automatic return to service).