ADLINK PCI-8124-C - Manual (Page 32)

22 Signal Connections
3.5 TTL Input Ports
There are 4 single ended TTL-level input ports on PCI-8124-C.
The following table shows the pin assignment of these TTL inputs.
The maximum input voltage of TTL-level input ports is 4.6VDC. So
user should not apply signals over this limitation.
CN1 Pin No. Name Description
21 TTL-IN1 TTL Level Input port 1
22 TTL-IN2 TTL Level Input port 2
46 TTL-IN3 TTL Level Input port 3
47 TTL-IN4 TTL Level Input port 4
25, 50 DGND TTL Input reference GND