VeriFone MX800 Series - Com2; Com3

DEVICE DRIVERS
COM Ports on the M
x
800 series of Terminals
M
X
800 SERIES PROGRAMMERS GUIDE 99
COM2
COM2, or device /dev/ttySAC1, supports the following hardware lines: RTS,
CTS, DTR, and DCD.
The RTS/CTS flow control is under the device driver control, and the RTS line
must be controlled by the application.
COM3
COM3, or device /dev/ttyWR0 has the additional ability to communicate with an
Electronic Cash Register utilizing the tailgate protocol. This is the only port that
can communicate using this protocol. As shown in the architecture diagram
above, COM3 is directly connected to another hardware device called a
Wrenchman F331 8051 device controller, which handles all of the tailgate
protocol. A special driver allows this port to function either as a generic RS232,
RS485, or SIO Tailgate device. It also allows special ioctl() commands to be
issued for configuration and obtaining information on the status of the port. Ioctl’s
for this port are also available with the SVC COM3 service functions and are
discussed later in this document.
NOTE
Due to limitations in the firmware, this port does not support “true” full duplex
mode and as a consequence, NO full duplex protocols should be used with this
port. If this port is connected to a full duplex device and a full duplex protocol is
used in communication, this port may not be able to transmit and received data
without any loss, depending on the amount of data and baud rate it is configured
for. If this port is connected to any device that is capable of full duplex mode but
uses a half duplex protocol in its communication (i.e. packet is sent, waits for
response such as Ack/Nak, packet is sent), then there is no problem of data loss.
Protocols and devices that do not use full duplex and can safely be connected to
this port are: ECR, Zontalk, DL, DL5, DDL, most COM devices, printers, and
check readers.
NOTE
All configuration of baud rates (listed in COM Ports on the M
x
800 series of
Terminals section), character sizes, parity and stop bits are supported except for
7 bits, No Parity, and 1 stop bit (7N1). This specific setting is not supported on
COM3. If it is desired to have the port configured for 7 bit character sizes with no
parity bit, then 2 stop bits (7N2) MUST be used instead.