User`s guide

port from the write function call. The host write functions will not
return until the message has been sent downlink. When using the
ALERT/ACK link protocol, interrupt latency is not a problem, since
the SLTA-to-host protocol includes an acknowledgment of the start of
the message. The driver employs timeouts in order to prevent lockout
of the write function, and timeouts for clearing various states of the
transmitter/receiver when line errors occur.
When operating at lower serial bit rates, it becomes less desirable to
disable interrupts for long periods.
The trade-off with using the full
interrupt mode is that other system interrupts may cause loss of data
in the serial port’s UART. If the /F option is specified, the driver uses
interrupts for every uplink and downlink byte transferred. Downlink
messages are buffered from the device write function and are sent
downlink under interrupt control. Uplink messages are received
under interrupt control and are buffered also. This option should be
used for serial bit rates of 9,600 bps or slower.
/M
Enables modem support and the reliable transport protocol. This
option must be specified if the host is to communicate with the
SLTA-10 Adapter via a modem connection. The SLTA-10 Adapter
must be configured with Switch2/CFG2 input in the Remote Host
setting (UP position). When connected, the selected SLTA-10 Adapter
and Host network interface link protocol is in effect. When
disconnected the only allowable link layer traffic is of the ‘modem
direct’ type, where ASCII strings are being exchanged between the
host and the modem, for example, AT commands to dial out. Any
other network interface traffic is not allowed when disconnected from
the SLTA-10 Adapter. Calls to the read function will result in no
network interface data messages (LDV-NO-MSG-AVAIL), and any call
to a write function that needs to communicate with the SLTA-10
Adapter via the modems will result in a No Output Buffers Available
error (LDV-NO-BUFF-AVAIL). Once the connection is made, normal
network interface traffic may resume.
This option also enables the reliable transport protocol. This protocol
includes the addition of a message sequence number and the end of
message ACWNACK code. See Chapter 4 for a description of this
protocol.
/N
/Q
Disables the ALERTjACK network interface link protocol, and
enables the buffered network interface link protocol. Network
interface messages are sent without waiting for the ALERT ACK
response. Both sides of the interface (the SLTA-10 Adapter and the
driver) must have the same setting. This option should not be used
with the lM option.
Allows modem responses to be sent uplink to the host. When the
telephone link is disconnected, these messages are ASCII strings with
the network interface command type niDRIVER (OxFO). If /Q is
specified, the host application must be able to handle messages, such
as NO CARRIER, that might come from the modem itself if problems
occur in the connection.
8-6
Using the DOS Driver with SLTA-10 MIP Mode