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A process controller that is communicatively coupled to an external field device via a communication network uses a shadow function block disposed within a process controller to enable implementation of a control routine that uses both an internal function block disposed within the process controlle

A process controller that is communicatively coupled to an external field device via a communication network uses a shadow function block disposed within a process controller to enable implementation of a control routine that uses both an internal function block disposed within the process controller and an external function block disposed within the external field device. The shadow function block includes a communication port that communicates with the external function block via the communication network to thereby receive data pertaining to the external function block, a memory that stores the received data according to a configuration protocol of the internal function block and an output that provides the stored external function block data to the internal function block according to the configuration protocol of the internal function block. The communication port of the interface function block may include an output that sends data generated by the controller or the internal function block to the external function block using the communication protocol associated with the external function block.

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A process controller that is communicatively coupled to an external field device via a communication network uses a shadow function block disposed within a process controller to enable implementation of a control routine that uses both an internal function block disposed within the process controlle

A process controller that is communicatively coupled to an external field device via a communication network uses a shadow function block disposed within a process controller to enable implementation of a control routine that uses both an internal function block disposed within the process controller and an external function block disposed within the external field device. The shadow function block includes a communication port that communicates with the external function block via the communication network to thereby receive data pertaining to the external function block, a memory that stores the received data according to a configuration protocol of the internal function block and an output that provides the stored external function block data to the internal function block according to the configuration protocol of the internal function block. The communication port of the interface function block may include an output that sends data generated by the controller or the internal function block to the external function block using the communication protocol associated with the external function block. ns paths; receiving the sequence of data packets at the receiving node; passing the received data packets directly to a receiving application if the received data packets have sequential packet numbers; and reconstructing the data packets into the transmitted sequence if the received data packets do not have sequential packet numbers, said reconstructing step including the steps of: storing a first data packet received out of sequence in a reconstruction buffer having a finite storage space with a beginning and an end;storing additional received data packets in the buffer in increasing numerical order from the beginning of the buffer;determining whether two or more stored data packets at the beginning of the buffer have sequential packet numbers;sending the two or more stored data packets with sequential packet numbers from the buffer to the receiving application;starting a packet timer, T1, at the receiving node when the first out-of-sequence data packet is received, T1 timing the longest permissible transfer time of a single packet through the network, and T1 being reset each time a sequential data packet at the beginning of the buffer is received, or the buffer is filled;determining whether or not T1 expires before a sequential data packet at the beginning of the buffer is received or the buffer is filled; andpassing any sequential data packets stored in the buffer to the receiving application if T1 expires before a sequential data packet at the beginning of the buffer is received, or if the buffer is filled.2. A method of preserving data packet sequencing when a plurality of data packets are transmitted over a plurality of data transmission paths between a sending node and a receiving node in a radio telecommunications network, said method comprising the steps of: labeling by the sending node, each packet being transmitted with an increasing sequence number; transmitting the packets from the sending node over the plurality of data transmissions paths to the receiving node; receiving a first data packet out of sequence at the receiving node; starting a packet timer, T 1, at the receiving node when the first out-of-sequence data packet is received, T1 timing the longest permissible transfer time of a single packet through the network, and T1 being reset each time a sequential data packet is received; time-stamping the first out-of-sequence data packet and storing it in a reconstruction buffer, said buffer containing storage space to store the maximum number of data packets that can be received before T 1 expires; storing subsequently received packets in the buffer in increasing numerical order from the beginning of the buffer; receiving a second data packet; determining whether or not the second packet is assigned a number that is sequential to the number of the first data packet; passing the first and second data packets from the buffer to the receiving application if the second packet is assigned a number that is sequential to the number of the first data packet, and the first and second data packets are at the beginning of the buffer; retaining the second data packet in the buffer if the second packet is assigned a number that is not sequential to the number of the first data packet, or if the first and second packets are sequential but not at the beginning of the buffer; determining whether or not the buffer is full; continuing to store received packets if the buffer is not full; if the buffer is full, determining if there are any sequences of packets that are not at the beginning of the buffer, and passing the sequence of packets that have the lowest sequential numbers to the receiving application; determining whether or not T 1 expires before a sequential data packet at the beginning of the buffer is received; passing any sequential data packets from the buffer to a receiving application if T 1 expires before a sequential data packet at the beginning of the buffer is received; starting an inactivity timer, T 2, whenever the buffer is empty, T2 timing a time period for the sequence number to repeat itself (wrap around); determining whether or not T 2 expires before another packet is received; and starting the method over if T 2 expires.3. A method of preserving data packet sequencing when a plurality of data packets are transmitted over a plurality of data transmission paths between a sending node and a receiving node in a radio telecommunications network, said method comprising the steps of: labeling by the sending node, each packet being transmitted with an increasing sequence number until a predetermined number of packets have formed a sequence; repeating the sequence numbers in subsequent sequences of packets; transmitting the packets from the sending node in a series of sequences, each sequence containing the predetermined number of data packets and repeating the sequential numbers assigned to each data packet within each sequence; receiving the transmitted packets in the receiving node; determining whether or not the received packets have sequential packet numbers; passing the received data packets directly to a receiving application if the received data packets have sequential packet numbers; and reconstructing the data packets into the transmitted sequence if the received data packets do not have sequential packet numbers by: storing the received data packets in a reconstruction buffer having a storage space with a beginning and an end, said received packets being stored in the buffer in increasing numerical order from the beginning of the buffer;determining whether two or more packets have sequential numbers and are stored at the beginning of the buffer;passing the two or more packets to the receiving application if they have sequential numbers and are stored at the beginning of the buffer;retaining the two or more packets in the buffer if they have sequential numbers and are not stored at the beginning of the buffer;determining whether subsequently received packets fill a gap between the beginning of the buffer and the two or more sequential packets; andpassing the two or more sequential packets and the subsequently received packets to the receiving application if the subsequently received packets fill the gap between the beginning of the buffer and the two or more packets.4. A method of preserving data packet sequencing when a plurality of data packets are transmitted over a plurality of data transmission paths between a sending node and a receiving node in a radio telecommunications network, said method comprising the steps of: labeling by the sending node, each packet being transmitted with an increasing sequence number; transmitting the packets from the sending node over the plurality of data transmissions paths to the receiving node; receiving the data packets at the receiving node; determining whether the received data packets have sequential packet numbers; passing the received data packets directly to a receiving application if the received data packets have sequential packet numbers; storing the received data packets in a reconstruction buffer if the received data packets do not have sequential packet numbers; starting a packet timer, T 1, at the receiving node when the first out-of-sequence data packet is received, T1 timing the longest permissible transfer time of a single packet through the network, and T1 being reset each time a sequential data packet at the beginning of the buffer is received, or the buffer is filled; determining whether or not T 1 expires before a sequential data packet at the beginning of the buffer is received or the buffer is filled; and passing any sequential data packets stored in the buffer to the receiving application if T 1 expires before a sequential data packet at the beginning of the buffer is received, or if the buffer is filled.5. In a data network in which a plurality of data packets