GDM-8261A User Manual 
124 
Digital I/O Terminal Configuration 
 
The digital I/O terminal outputs the result of  Compare 
measurements to control external devices. By providing 
separate VCC power for the terminal, the outputs can also be 
used as a power source for TTL and CMOS circuits. 
Connector type: DB-9 
female 
6
FAIL Out
7 8 9
1
2 3 4 5
High Limit FAIL Out
VCC Out
NC
PASS Out
External Trigger In
EOM Out
LOW Limit FAIL Out
Digital (chassis) Ground
VCC output, 5V. Serves as the unregulated max 
power source for the external device/logic. 
Without GPIB/LAN card: 4.5V/50mA 
With GPIB/LAN card: 4.0V/50mA 
Digital (chassis) Ground. 
External Trigger Input. Accepts external trigger 
signals. For using external signals, see page 119 
(Scanner) or page 76 (Configuration). 
Pins 5-9 use open-collector outputs and thus 
require a pull-up resistor for each pin. The 
output resistor must have a minimum rating of  
500Ω. All the outputs are active low. 
Pins 5-9 
output 
wiring 
diagram 
Pin 1
Pin 5-9
Vo
R(min: 500Ω)
Digital I/O 
Terminal
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