Specifications

X723-300151 4-2 Issue 2

patchfields for LIU to system controller, or LIU to LIU communications.

Several LIUs, for example, could broadcast the polling sourced by the

system controller patchfield. The response from any of the LIUs will be

fed back to the system controller patchfield via a logical ‘ANDing’

arrangement inside the LIU patchfields and a wired OR connection to the

Mbus. It should be noted that all nodes that have not been polled, return

a Null response which is to output logic 1 continuously. This allows all the

poll responses to be groomed together via the ‘ANDing’ functions of the

patchfields and wired OR’ed Management bits. A block diagram of the

management patching facilities are shown in Figure 4-1.

4.2 System Controller Patchfield

The patchfield on the system controller routes management data between

the backplane management bus, the V.28 inputs and outputs on the

network port and the three UARTs used for system controller access to

the management data. There are seven patchfields from which one may

be selected for each management configuration. The default patchfield

number is stored in an E

PROM which also contains the default patchfield

numbers for the Dual LIU patchfields when in port 1 or 2.

UART A and UART B are used for network management or when

operating as a remote unit, while UART C is used for the local RS232 port.

Table 4-1 shows the patchfields that have been pre-programmed into the

system controller management firmware DT990C.

The standard patchfields on the system controller use the COM 1 V.28 I/O

port, the M1 bus line and UART A for management branch A, and the

COM 3 V.28 I/O port, the M3 bus line and UART B for management

branch B.

Electrical diagrams of the patchfields can be found in Appendix A.