ORTEC Easy-MCS, Hardware User Manual

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Easy-MCS
™
Multichannel Scaler and MCS-32 (A73-B32) Software 931054C / 1213
8
START IN Accepts a TTL signal to start the scan on the next clock edge after the falling edge
of the transition from +2.5 V to 0 V is detected on the START IN. In the Internal Dwell mode
the next clock edge is obtained from the 50-MHz internal time base. For the External Dwell
mode, the next clock edge is obtained from the External Channel Advance Input. The START
IN edge is ignored during a scan or when disabled by the Start Enable Input. Input impedance is
1000
Ω
to ground. Minimum pulse width is 10 ns.
STOP IN Accepts an external TTL input rising from 0 to +2.5 V to stop scanning at the end of
the current scan. Minimum pulse width is 10 ns. Input impedance is 5000
Ω
to ground.
CHN ADV IN (Channel Advance Input) Accepts an analog or digital pulse to cause a chan-
nel advance when the signal crosses the threshold with a positive slope (provided External
Dwell has been selected in the MCS-32 software). Threshold is adjustable from
!
1.6 to +3 V
in 1.5 mV steps via the computer. Minimum dwell time is 100 ns. Minimum pulse width
is 10 ns. Minimum pulse amplitude is 30 mV. Input impedance is 1000
Ω
to ground.
GATE IN Accepts a TTL input to prevent counting of the signals at the IN and SCA IN
connectors. When the GATE IN is <0.8 V, counting is inhibited. Counting is enabled when the
GATE IN level is >2 V, or when the GATE IN is not connected to signal source. Input
impedance is 1000
Ω
to +5 V.
TTL (START ENABLE INPUT) Accepts a TTL input to enable/disable response to a START
IN trigger. When the START ENABLE INPUT is <0.8 V, triggering is inhibited. Triggering is
enabled when the START ENABLE INPUT level is >2 V, or when the START ENABLE
INPUT is not connected to a signal source. Input impedance is 5000
Ω
to +5 V. START
ENABLE INPUT must be at the desired level when the rising edge of the START IN arrives.
2.1.2. Outputs
All outputs are supplied on the 25-pin D connector on the rear panel. The MCS-PCI-OPT2
option offers convenient BNC connections to the D connector.
START OUT This TTL ouput rises from <+0.4 V to >+2.4 V when a scan starts, and returns to
<+0.4 V after 160 ns. Useful for synchronizing external instruments with the start of the scan.
The output is short-circuit protected and can drive impedances
$
50
Ω
.
CHN ADV OUT (Channel Advance Output) This TTL output rises from <+0.4 V to >+2.4 V
when the Easy-MCS advances from one channel to the next. The pulse width is approximately
20 ns. The output is short-circuit protected and can drive impedances
$
50
Ω
.
SCA OUT A TTL output pulse for every SCA IN signal that occurs between the upper and
lower discriminator thresholds. The output rises from <+0.4 V to >+2.4 V as the SCA IN signal