SLTA-10 Adapter User’s Guide 71
The pacing delay will have no effect unless it is greater than the actual period
it takes to transmit a single byte at the given serial bit rate. The time taken to
transmit a byte is 173 µs at 57,600 bps, and 86 µs at 115,200 bps. This option
should be used at 115,200 bps if messages greater than 16 bytes are to be
transmitted. A value of /W120 is suggested. This option is not required at the
serial bit rate of 38,400bps or slower.
/Z
By default, the SLTA-10 MIP mode firmware disables network
communications after a reset by entering a FLUSH state. This state causes
the SLTA-10 Adapter to ignore all incoming messages and prevents all
outgoing messages, even service pin messages. The SLTA-10 MIP mode
network driver for DOS automatically enables network communications when
the SLTA-10 Adapter is opened and when it receives an uplink message from
the SLTA-10 Adapter indicating that it has been reset. However, the host
application itself must explicitly enable network communications if the
/Z
option is specified and the Switch3/CFG1 input is set to
Network Disable
(UP
position). See Chapter 4 for more information.
Host applications which need to configure the SLTA-10 Adapter prior to
enabling network communications should use this option. This option should
not be used with the LonManager API, LonManager LonMaker, or the
LonManager DDE Server. More information about the niFLUSH_CANCEL
message is provided in the
L
ON
W
ORKS
Host Application Programmer’s Guide
.
Network Interface Protocol Options
/F
Enables the full interrupt mode of the driver. If this option is not specified, the
driver will disable interrupts for the duration of each link-layer transfer. This
ensures that no data will be lost due to other system interrupts, and is
acceptable at high serial bit rates. The driver will use interrupts for the first
byte of each uplink interface buffer. When the uplink interrupt is received, the
driver reads the rest of the message without interrupts via polled I/O.
Interrupts are disabled during the uplink transfer. This assures that no other
system interrupts will occur resulting in lost uplink data frames. Downlink
transmissions are sent directly via polled I/O of the serial 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
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