Specifications

Programmer’s Guide Model 181 Series 180 Communications
TransAct Technologies
09/26/2000 Page 8 - 1
Appendix A
Communications
OVERVIEW
In order for a receipt to be printed, a printer must be able to accept a data stream
containing characters and commands that the host computer wished the printer to
print. This chapter describes the various interfaces to allow this transmission of
data.
INTERFACES
In order for the printer to communicate with the host, a communication link must
be established. The Model 181 supports the following three communication
interfaces:
 RS-232C Interface
 Parallel Interface
 USB
Each of these has a protocol associated with it that the host must understand and
adhere to. Only when the interface parameters are matched and the proper
protocol is used will the host and the printer be able to communicate. See the
respective sections in this chapter for a description of the protocol associated with
each type of interface.
RS-232C INTERFACE
The RS-232C interface uses either RTS/CTS, DTR/DSR or XON/XOFF
protocol. For RTS/CTS, changes in the RTS/CTS signal coordinates the
information flow. For DTR/DSR, changes in the DTR/DSR signal coordinates the
information flow. For XON/XOFF, data characters transmitted between the Host
computer control communication data flow.
The RS-232C version of the Model 181 offers the standard communications
options which are configured in the non-volatile eeprom memory.
RTS/CTS PROTOCOL
The RTS signal is used to control data transmission to the printer. It is driven
High when the printer is ready to receive data and driven low when it cannot
accept any more data. The host will transmit data to the printer when it
recognizes the state of the printer RTS signal is high.