USB-I/O Interface Adapter GPIO-24. Programmer's Reference Manual.
 6.2.6. GPIO_IN_EV_CHANGE (0x05) – Sending events when input value of the pin
changes |  | 6.4. GPIO_SET_IN_CFG (0x05)  |
USB-I/O adapter digital input pins have either TTL or Schmitt
Trigger buffer. Refer to I/O Pinout table to determine the input
type for each specific pin.
Electrical characteristics of digital input pins are specified in the following table:
| Characteristic | Min | Max | Units | Condition |
| Digital input low voltage: | ||||
| Pins with TTL buffer | VSS | 0.8 | V | JP3 open |
| VSS | 0.5 | V | JP3 close | |
| Pins with Schmitt Trigger buffer | VSS | 1.0 | V | JP3 open |
| VSS | 0.66 | V | JP3 close | |
| Digital input high voltage: | ||||
| Pins with TTL buffer | 2.0 | 5.0 | V | JP3 open |
| 1.65 | 3.3 | V | JP3 close | |
| Pins with Schmitt Trigger buffer | 4.0 | 5.0 | V | JP3 open |
| 2.65 | 3.3 | V | JP3 close | |
| Input leakage current | - | ±1 | µA |
VSS ≤ VPIN ≤ VDD pin at high-impedance |
