scope:

This document specifies the electrical, data and timing interface between the control unit of a postal sorting system and an ink jet printer connected to that system. It further specifies an ancillary interface to the printer, which can be used for the support of remote diagnostics and other service functions. At the physical level, the specification is based on the use of a combination of a standard 100 Mbps Ethernet connection for the transfer of data and patch cables for signalling. At a logical level, data is transferred using messages transmitted across the Ethernet connection using three TCP/IP sockets, with the execution of timecritical functions being controlled through the use of signals on a TIA/EIA-422 interface. This document defines all messages that may be transferred via each of the TCP/IP sockets, specifies printer behaviour on receipt of these messages and defines how the timing of this behaviour is controlled by the TIA/EIA-422 signals. The specification supports the use of the printer to print bar codes, human readable text and/or images on mail items whilst these are being transported past the print head3. It provides explicit support for Bar/No Bar (BNB), Bar/Half Bar (BHB) and four state bar codes, but allows full user control over the specification of bar patterns to support more complex bar coding formats. The different TCP/IP sockets have different functions that may be fulfilled by different subsystems referred to as sorter control, print control and remote service. Where these are implemented as distinct subsystems, they will need to intercommunicate. The interfaces between them nevertheless fall outside the scope of this specification and are not covered herein. This specification does not address the physical construction of printers or their mechanical integration into sorting systems, neither does it specify electrical power connections to the printer.