Hardware 7-11
External TTL BNC Connectors
NetScans rear panel provides two external trigger BNC connectors. The BNC TTL Scan output is used for
synchronizing equipment with NetScan. NetScan can be programmed to trigger on a rising or falling TTL level.
Any TTL level signal (> 2.2V = Hi, < 0.8V = Lo) may be used as a trigger pulse. A trigger pulse may also be used
to generate a Service Request. Note that the TTL Out is a LS-TTL compatible output, 0.4 mA sourcing, 8 mA
sinking. When a scan is logged into the acquisition buffer (after the actual scan), the TTL output signal is pulsed for
100 ms. Refer to the following trigger timing diagram.
Signal Conditioning Cards
NetScan and its expansion chassis can each house a quantity of 4 signal conditioning cards (8 total, for a possible
128 channels). The signal conditioning cards can be varied using any combination of the following 5 types.
CSN/14/TC/P Thermocouple and low volts card for units with subminiature-plugs
CSN/14/LV/T Low volts card with removable screw terminals
CSN/14/LV/B Low volts card with BNCs
CSN/14/LV/S Low volts card with safety jacks
CSN/14/HV/S High volts card with safety jacks
Each scanning module fits into the metal, shielded chassis. The chassis insulates the cards from noise and maintains
a constant internal temperature.