Agilent / HP / Keysight E1332A

This counter / totalizer will provide seven counter functions and the funtions are frequency (up to 4 MHz), period average, pulse width, time interval, totalize, gated totalize, and up/down count.

When using this module, you select the isolated or direct inputs through software commands.

A total of eight channels can be connected to one counter card by multiplexing between four isolated channels and four non isolated channels.

The digital input low pass filter will also be software selectable with Pass Frequency in 16 binary steps from 4Hz to 131KHz.

It filters out the high frequency noise of input signals, which would be the bounce of mechanical switches.