Introduction

The dual MUX interconnect panels or cables are designed to allow two ACC cards to be connected to a single network port. The interconnect panel is typical used to connect two ACC cards installed in two separate HP 9000 systems, but the panel can also connect two cards in the same system. (This may be useful for prototyping and test situations.)

Each output port on the dual MUX interconnect panel or cable may be controlled by either ACC MUX card, but care must be taken that both MUX cards don't attempt to access or control the same port at the same time. One MUX card must have the port configured as being in “loopback” mode (tri-state), and the other must have the port configured as being in “RS232”, “X21”, or whatever mode is appropriate.

In order for a port to be handed off from one card to the other, the port being controlled must be put into “Loopback” mode from the card that is currently controlling it. The port can then be placed into the appropriate mode (such as RS232 or X21) by the other card, which can then begin controlling it.

The following sections describe how the control of MUX ports may be shared between the two cards or handed off from one card to the other.