摘要:
An apparatus communicates with an advanced switching (AS) fabric. The apparatus includes a transmit engine that generates a request packet for transmission to the AS fabric. The transmit engine associates a first transaction identifier with the request packet. A receive engine receives a reply packet in response to the request packet. The reply packet contains a second transaction identifier. The receive engine compares the first transaction identifier to the second transaction identifier. If the first transaction identifier matches the second transaction identifier, the receive engine decides to store data from the reply packet at an address associated with the first transaction identifier.
摘要:
Circuitry is used for generating one or more commands to access a ring buffer on an end node device of an advanced switching (AS) fabric. The circuitry includes circuits to receive information for accessing the ring buffer and to generate a current command based on the information. The information includes an address of the ring buffer and a length of data associated with buffer access. The circuitry also includes a controller to determine whether the information is for one command or for plural commands. If the information is for plural commands, the circuits generate the plural commands by updating the information following generation of the current command and by generating a subsequent command using updated information.
摘要:
An apparatus communicates with an advanced switching (AS) fabric. The apparatus includes a transmit engine that generates a request packet for transmission to the AS fabric. The transmit engine associates a first transaction identifier with the request packet. A receive engine receives a reply packet in response to the request packet. The reply packet contains a second transaction identifier. The receive engine compares the first transaction identifier to the second transaction identifier. If the first transaction identifier matches the second transaction identifier, the receive engine decides to store data from the reply packet at an address associated with the first transaction identifier.
摘要:
A lightweight structure for the base of a co-ordinate measuring machine is formed of a triangulated space frame arrangement using carbon fibre reinforced plastics bars (30) having a near zero coefficient of thermal expansion. The frame arrangement may be covered by a skin extending across one or more faces of the frame members to form a closed structure.
摘要:
Monitoring the state of a queue includes (a) determining when values of a head pointer of the queue and a tail pointer of the queue are consistent with the queue being either empty or full, (b) storing a state responsive to changes in at least one of the head pointer and the tail pointer, and (c) when the values of the head pointer and the tail pointer are consistent with the queue being either empty or full, using the stored state to distinguish between the queue being empty and the queue being full.
摘要:
A dimensional measuring and checking machine mounts a bridge structure (12) on legs (22) which are supported on a base (10) by air bearings. The varying forces due to travel of a probe mounting carriage (24) create vertical displacements of the bearings and movement of the bridge (12) out of alignment. To compensate for this, and thus enable high accuracy measuring, a chain (34) moves with the bridge (12), rotating a spindle (42) at one end of the machine, and thus moving the legs (22) at that end so levers (48) and pivot blocks (52) vary the height of the bridge (12).
摘要:
Assembling packets includes determining portions of the packets in parallel. Determining portions of the packets in parallel includes determining a first header portion of the packets in parallel with determining a second header portion of the packets. Corresponding ones of the determined portions are combined to form the packets.
摘要:
In a co-ordinate measuring machine, a linear guideway comprises two tubular guides 14, 16 mounted on a column 10 in a parallel spaced apart relation and extending in a direction parallel to the longitudinal axis of the column 10. The guides 14, 16 are mounted on the column 10 by a plurality of elongate bars 20 formed for example of carbon fibre. The bars 20 are so designed as to allow change in relative length between the guide 14 and the column 10 but to retain the guide 14 in a rigid relation to the column 10 in a direction along the axis of each of the bars 20. The guide 16 is mounted on the column 10 by a plurality of pairs of bars 50 similar to the bars 20. Each of the guides 14, 16 is anchored relative to the column 10 at one respective end. A carriage 12 is slidably mounted on the guides 14, 16 by suitable bearings and requires five degrees of restraint and one degree of freedom in the axial direction of the guides 14, 16. The guide 16 offers two degrees of restraint and the guide 14 offers one degree of restraint but, in conjunction with the guide 16 controls rotation about the axis of the latter. A bearing arrangement controls rotation about the other two axes making five restraints in total.
摘要:
An apparatus generates a data packet for an advanced switching (AS) fabric. The apparatus includes a direct memory access (DMA) engine that retrieves a descriptor from a queue, and that stores the descriptor in a storage area. The descriptor contains information used to build the data packet. A work manager retrieves the descriptor from the storage area, and works to generate the data packet using the descriptor.
摘要:
In a co-ordinate measuring machine a base structure (10) supports guideways and carriages providing for movement of a probe adapted to contact a workpiece, and a separate structure (20) is provided for supporting the workpiece itself. The structure (20) can be supported directly on a foundation (16) by an arrangement of bars (54) capable of restraining all six degrees of freedom of movement of the structure (20), i.e. straight line movement in each of the X, Y and Z directions and rotation about each of the X, Y and Z axes. Each bar (54) is stiffened in the direction of its own axis but enables compliance in all directions normal to this axis to accommodate small movements of the structure (20) without stress or strain. The base structure (10) is mounted on the workpiece structure (20) by a similar arrangement of the bars (54) which thereby restrain all 6.degree. of freedom of movement of the base structure (10). There is thereby avoided relative movement between the base structure (10) and the workpiece structure (20) which would otherwise result in loss of measurement accuracy to an extent significant in high accuracy measuring and checking machines.