XECOM
(9)
XE24S500
Transmitter
Receiver
TXD
RXD
TXD
RXD
Description
AT#T01<cr>
Initiate File Transfer
:<cr>
FILE<cr>
Link Established
abc...z
abc...z
File Data
3 sec pause in data
A718<cr>
Checksum at End of File Transfer
OK<cr>
File Transfer Successful
or
ERROR<cr>
Error Detected in File Transfer
Note: In the above example that the file transfer is assumed to be completed when three seconds pass with
no data being presented to the TXD input on the serial port.
XE24S COMMUNICATIONS CONTROLLER (continued)
Sample File Transfer
Multipoint Network
System designers can create a point-to-multipoint network with up to 253 remote nodes. The master node
is assigned address 1. The remote nodes use addresses 2 to 254. For efficient network operation, Count-
Off™ allows the master node to poll the entire network in under 10 seconds.
Count-Off™ permits the master node in a point-to-multipoint system to quickly check the status of all
network nodes. It creates a temporary time division multiplexing scheme which permits each node to
report its status without the handshaking sequence normally required for a wireless data exchange.
Count-Off™ is initiated by the AT#C command, from the host system. The master node broadcasts the
command to all network nodes. Upon receipt of the command each remote node initializes an internal
timer. Then in sequence by address each node transmits an 8-byte status message. The status message
is programmed with the AT#E: or AT#E= command. The status byte is passed to the host system in the
correct sequence upon receipt of the Count-Off message from the master node.
Using Count-Off™ network reporting will be completed in less than 10 seconds. Based on the status
information the host can then elect to service any of the remote nodes.
Master
Node 1
Node 6
Node n
Node 8
Node 7
Node 9
Master
Node 1
Node 2
Node 3
Node 4
Node 4
Node 5
Node 6
Node n
Node 8
Node 7
Node 9
Master
Node 1
Node 2
Node 3
Node 4
Node 4
Node 5
Node 6
Node n
Node 8
Node 7
Node 9
T
0 - Master Broadcasts
Count-Off Initiation
T
1 - Node 1 Transmits
8-Byte Status
T
2 - Node 2 Transmits
8-Byte Status
T
n - Node n Transmits
8-Byte Status
Count-Off Complete
COUNT-OFF™ SEQUENCE
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