Protocol for extended data transfer in scan-based industrial controller I/O system
AssigneeRockwell Automation Technologies, Inc.
InventorsRick Ales, Robert J. Kretschmann
Life of this patent
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Abstract
Extended low priority data is integrated into high priority I/O data in a scanned data transfer protocol using regular transmission fixed data blocks by allocating as little as a single word of the data block to the sequential transmission of this low priority data. Low priority data is buffered on both sides of this transmission to allow it to be transmitted over the course of many data block. As a result, the regular and predictable transfer of input and output data is not upset while allowing arbitrarily large low priority data to be sent at a relatively low data rate.
Claims13
An industrial control I/O system for use with I/O modules attachable to a backplane, the I/O modules transmitting real time electrical values to an industrial process via outputs of the I/O module determined by an I/O data unit, the I/O system comprising:
- a backplane having connector slots receiving I/O modules and providing data conductors and slot address signals specific to a connector slot;
- an adapter connected to the backplane and executing a stored program to:
- (a) receive an I/O data unit for transmission over the backplane to an I/O module;
- (b) receive a low priority data unit for transmission over the backplane to the I/O module;
- (c) form a transmission data block of predetermined length incorporating the entire I/O data unit and only a portion of the low priority data unit smaller than the I/O data unit;
- (d) sequentially enable the slot address signals to each connector slot at a predetermined scan rate;
- (e) when the slot address signal to a connector slot holding the I/O module is enabled, transmit the transmission data block to an I/O module in the connector slot;
- and
- (f) repeat step (a) and (c)-(e) where at step (a) a new I/O data unit is received and wherein at step (c) the transmission data block holds the new I/O data unit and a different portion of the low priority data unit, the repetition proceeding until the complete low priority data unit has been incorporated into different data block and transmitted to the I/O module in the connector slot;
- whereby low priority data of arbitrary size can be integrated into a fixed scan based backplane without compromising the delivery of real-time I/O data.
An I/O system for use with I/O modules attachable to a backplane, the I/O modules communicating to an industrial process real time electrical values at outputs of the I/O module determined by an I/O data unit, the I/O system comprising:
- a backplane having connector slots receiving I/O modules and providing data conductors and slot address signals specific to a connector slot;
- an adapter connected to the backplane and executing a stored program to:
- (a) receive an I/O data unit for transmission over the backplane to an I/O module;
- (b) sequentially enable the address lines to each connector slot at a predetermined scan rate;
- (c) when the address line to a connector slot holding a given I/O module is enabled, receive identification information from the given I/O module indicating whether it can accept extended low priority data transmissions;
- (d) only when the given I/O module can accept extended low priority data transmissions:
- (1) receive a low priority data unit for transmission over the backplane to the I/O module;
- (2) form a transmission data block of fixed length holding the entire I/O data unit and only a portion of the low priority data unit smaller than the I/O data unit;
- (e) only when the given I/O module cannot accept extended low priority data transmissions:
- (1) form a transmission data block of fixed length holding the entire I/O data unit without a portion of a low priority data unit;
- (f) transmit the transmission data block to an I/O module in the connector slot;
- whereby I/O modules accepting the piecewise transmission of low priority data units may be intermixed on the backplane with I/O modules not accepting the piecewise transmission of low priority data units.
An I/O module receiving real time electrical values from an adapter over a backplane, the electrical values providing outputs of the I/O module determined by an I/O data unit to an industrial process, the I/O module comprising:
- a connector adapted to connect physically and electrically to a connector slot of the backplane to communicate with data conductors and slot address signals specific to a connector slot;
- a backplane communication circuit executing a stored program to:
- (a) receive a data block over the backplane upon enabling of a slot address signal associated with the connector slot to which the I/O module may be connected;
- (b) extract an I/O data unit from the data block;
- (c) update outputs of the I/O module according to the I/O data unit;
- (d) extract a portion of a low priority data unit from the data block;
- and
- (e) store the portion of the low priority data unit to other stored portions of the low priority data block until all portions of the low priority data block have been received.
Dependencies are inferred from the claim text.