Справочное Руководство для LXE 1280
214
Protocol Messages
LDS Plus Reference Guide
E-SW-LDSPLUSRG-G
XON and XOFF Control Type
The XON and XOFF control sequence can be sent to the network device at any time while
operating in the full duplex or full duplex/half duplex modes. If the network device is operated in
the half duplex mode then XON and XOFF are not accepted while the network device is
transmitting data to the host.
operating in the full duplex or full duplex/half duplex modes. If the network device is operated in
the half duplex mode then XON and XOFF are not accepted while the network device is
transmitting data to the host.
The XON and XOFF codes cannot be imbedded within a valid message string. If the network
device receives a SOL “<” character it will not accept XON or XOFF until it receives an EOL
C
device receives a SOL “<” character it will not accept XON or XOFF until it receives an EOL
C
R
L
F
character. In this instance the network device will abort the message and return a non-
printable character error code.
If a valid XOFF character is received by the network device it will halt all further transmissions to
the host for 2.55 seconds or until it receives a valid XON character. If data is in the process of
being transmitted to the host it will be halted at the next transmitted character, therefore it will be
necessary for the host to accept one additional character after sending the XOFF.
the host for 2.55 seconds or until it receives a valid XON character. If data is in the process of
being transmitted to the host it will be halted at the next transmitted character, therefore it will be
necessary for the host to accept one additional character after sending the XOFF.
The host may send successive XOFF characters, at intervals less than 2.55 seconds, to disable the
network device indefinitely.
network device indefinitely.
When the host has sent a valid XOFF character to the network device it may send XON any time
before the 2.55 second timeout. When the network device receives the XON character it will set a
delay equal to the RX to TX enable time (F23) before resuming transmission toward the host.
before the 2.55 second timeout. When the network device receives the XON character it will set a
delay equal to the RX to TX enable time (F23) before resuming transmission toward the host.
Host to Network Device Protocol Message Type
Refer to the following table for a description of each host to network device protocol message and
the network device response:
the network device response:
B – Busy
Busy message. Waits 2.5 seconds before sending any more data messages.
L – Start System
Starts system operation. Sends an L protocol message back indicating to the host that it is back
on-line.
on-line.
O – Stop System
Stops system operation. Sends an O protocol message back indicating to the host that it is now
off-line.
off-line.
QC – Clear Host Counter
Clears host counters. Clears only the host counters.
QR – Request Host Counter Value
Requests host counter values. Sends only the host counter values.
R – Roger
Rogers a message. Removes the current inbound data message from its output buffer.