An I/O port is used to connect the PXB with an external instrument such as a signal generator, signal analyzer, or digital signal interface module (DSIM).
There are two I/O ports on each I/O card that is installed in the rear panel of the PXB. The PXB may have from one to four I/O cards installed. The I/O cards must be installed sequentially, from the top slot to the bottom slot, in the rear panel of the PXB.
These rear panel slots are labeled A, B, C, and D, sequentially from top to bottom.
The I/O cards are also labeled. The left side of the I/O card is labeled Ch 1 and the right side of the I/O card is labeled Ch 2.
This labeling is used by the firmware to identify each I/O block in the block diagram. When the firmware identifies the I/O port as "Port A1", this indicates that the port being called out is "Ch 1" on the left side of the I/O card that is installed in the top I/O slot.
I/O ports are used as an:
Input I/O - Receives signals from an instrument to be processed in the PXB
Output I/O - Sends signals to an instrument after the signal has been processed in the PXB