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.NOTE 1This specification can equally be applied to the interfacing of printers to sequencing systems and combined sorting and sequencing systems. It was primarily developed for application to ink jet printers, but could be applied to printers with similar functionality that make use of other printing technologies.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 time-critical functions being controlled through the use of signals on a TIA/EIA-422 interface.NOTE 2Several printers can be connected to a single sorting system. In this case, the printers can optionally share access to a single Ethernet network, but each requires its own patch cables. This standard does not support the connection of a single printer to multiple sorting system control units.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......