Numeric and text paging with an integral PLC modem

A method, comprising:

• formatting a paging message according to a paging message specification provided by a programmable logic controller, the paging message comprising a data value determined from a data variable defined in the paging message specification, the paging message formatted at a first modem directly connected to an expansion I/O bus of the programmable logic controller, the expansion I/O bus distinct from and not directly connected to a communications port of the programmable logic controller, the expansion I/O bus configured to communicatively connect to a plurality of I/O modules;
• and
• transmitting the formatted paging message from the first modem via a communications network.

A method, comprising:

• formatting a message according to a message specification provided by a programmable logic controller, the message comprising a data value determined from a data variable defined in the message specification, the message formatted at a first modem directly connected to an expansion I/O bus of the programmable logic controller, the expansion I/O bus distinct from and not directly connected to a communications port of the programmable logic controller, the expansion I/O bus configured to communicatively connect to a plurality of I/O modules;
• and
• transmitting the formatted message from the first modem via a telephone network.

A method, comprising:

• formatting a message at a first modem directly connected to an expansion I/O bus of a first programmable logic controller, the expansion I/O distinct from and not directly connected to a communications port of the first programmable logic controller, the expansion I/O bus configured to communicatively connect to a plurality of I/O modules;
• and
• transmitting the formatted message from the first modem via a communications network.

A system, comprising:

• means for formatting a message at a modem directly connected to an expansion I/O bus of a programmable logic controller, the expansion I/O bus distinct from and not directly connected to a communications port of the programmable logic controller, the expansion I/O bus configured to communicatively connect to a plurality of I/O modules;
• and
• means for transmitting the formatted message from the modem via a communications network.

A computer-readable medium containing machine executable instructions for activities comprising:

• formatting a message at a first modem directly connected to an expansion I/O bus of first programmable logic controller, the expansion I/O bus distinct from and not directly connected to a communications port of the programmable logic controller, the expansion I/O bus configured to communicatively connect to a plurality of I/O modules;
• and
• transmitting the formatted message from the first modem via a communications network.