CPUM  200-595-074-322

VIBRO-METER     CPUM  200-595-074-322  CPU Controller

General overview

The VM600 MPS uses a 6U 19″ system rack (ABE04x) with a custom-designed backplane

that combines features of a VME backplane and other special features to support the Meggitt

vibro-meter® product line (see Figure3-3 and Figure3-4).

This backplane consists of 3 different systems:

• A VME bus (P1)

• An analog bus (P3)

• Through connections between P2 and P4

The P1 bus, on the front side of the backplane, is used for slots0to14 in order to implement

a standard VME bus on the front side of the backplane. This corresponds to the VME16

specifications and allows 24-bit address and 16-bit data transfers between cards in the rack.

The P2 and P4 connectors are used for slots0to14 in order to connect the card in the front

card cage to the card immediately behind it in the rear card cage (through connections).

Slots15and18 of the rack are reserved for RPS6U rack power supplies. The backplane is

equipped with special high-current connectors (type H15) for these power supplies.

The P3 bus, on the rear side of the backplane, actually consists of the following three buses:

1-The Tacho Bus

The Tacho Bus is composed of 8 lines with passive terminations and is common to all

slots in the rack.

See 3.4.2Tacho Bus for further information.

2-The Open Collector (OC) Bus

The Open Collector (OC) Bus is composed of 96 open collector (“ground/open”) lines

without terminations.

The OC Bus is sub-divided into 6 buses each having 16 lines (these buses are called

OCA, OCB, OCC, OCD, OCE, OCF). Each of these six buses is associated with three

rack slots (with each rack slot associated with only one bus).

See 3.4.3Open Collector Bus for further information.

3-The Raw Bus

The Raw Bus is composed of 32×2 lines without terminations and is common to all slots

in the rack.

See 3.4.4Raw Bus for further information.

The Tacho Bus, the Open Collector Bus and the Raw Bus are not buses in the

microcomputing sense of the term, that is, there is no protocol, handshaking, timing and so

on. Rather, they should be thought of as groups of lines that can be used to transmit signals

The Tacho Bus contains 8 parallel bus lines and is common to all slots in the ABE04x system

rack.

The Tacho Bus is primarily intended for the sharing of speed and phase reference signals

between various cards in the rack, such as between MPC4/ IOC4T card pairs and/or

XMx16/XIO16T card pairs. Six Tacho Bus lines are available for speed/tacho signal sharing:

buslines1to6.

For example, speed signals can be put onto the Tacho Bus from an IOC4T card. This is done

by multiplexers that are under software control (see Figure3-5). These multiplexers allow

one or both of the “local” speed signals on IOC#A to be sent to another card, for example to

IOC#B. Software-controlled demultiplexers on IOC#B allow the speed signal to be brought

off the bus and onto the card. Once on IOC#B, these signals can be used by the

corresponding MPC4 card (MPC#B). This technique is known as using “remote” speed

signals.

The Tacho Bus is also used for the routing of cold-junction compensation (CJC) signals

between AMC8/ IOC8T card pairs. Two Tacho Bus lines are reserved for CJC signal sharing:

buslines7and8