User`s guide

running DOS or Windows cannot guarantee receipt of all characters in an input
stream appearing back-to-back on a COM port . ALERT/ACK link protocol (down
position) is the default setting for the SLTA-10 Adapter. When the SLTA-10 Adapter
uses the ALERTlACK protocol and it wishes to send data to the host, it first sends a
single ALERT character (hex 01).
The host then responds with an ALERT ACK
character (hex FE) to indicate its readiness to accept the rest of the data.
The
ALERT/ACK protocol places timing requirements on the host, and if these timing
requirements are violated, a driver error occurs. After the host network driver has
sent the ALERT ACK character, it enters a tightly controlled loop for accepting the
remaining characters-usually with interrupts disabled.
If this option is enabled
(switch in down position), the ALERT/ACK protocol will also be used when the host
wishes to send data to the SLTA-10 Adapter.
The buffered link protocol (up position) is designed for host computers and applications
that can accept and buffer back-to-back serial data without losing characters. For
example, most real-time operating systems and / dev/ t ty
drivers in UNIX systems
have this capability. In this case, the SLTA-10 Adapter simply sends the uplink
message without any handshake with the host. The SLTA-10 Adapter does not support
hardware handshake or XON/XOFF software flow control when directly attached to a
host. If the buffered link protocol option is enabled (up position), the buffered protocol
is also used when the host wishes to send data to the SLTA-10 Adapter. The buffered
link protocol should not be used when CFG2 is set to the Remote Host state
(up position). See Buffered Link Protocol in Chapter 9 for additional application
restrictions when using the buffered link protocol.
Modem Support (Switch 2 / CFG2)
Remote Host (modem)
Local Host
(default)
Figure 4.3 SLTA-10 Adapter Host Switch2 / CFG2
Switch2 / CFG2 controls the use of the SLTA-10 Adapter with a modem. If the
SLTA-10 Adapter is connected directly to a host, then CFG2 should be set to the
Local Host state (down position). This is the SLTA-10 Adapter default. If the
SLTA-10 Adapter is connected to a modem, then CFG2 must be set to the Remote
Host state (up position) and CFG3 must be set to ALERTjACK (down position).
SLTA-10 Adapter User’s Guide
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