User Manual

“Halo” System: Communication Protocol 970-00002-000
EXI Wireless Systems, Confidential Page 30 of 33 July 27, 1999
x x x x 0 1 1 0
Enter Reader mode (Controller only)
Restart Pre-alarm mode (Elevator only)
x x x x 0 1 1 1
Retransmit last Tag
x x x x 1 0 0 0
None
7.5.5. Device Data
This message is sent as a response to the “Send / Request Data” message. It follows request message
within 150 µs. The length of this message is not predictable and it depends on system activity. Any TIC or
TIF alarms are reported with this message and if multiple TIC or TIF alarms are available in the RIM’s
buffer, they will be all sent within one message.
Fixed portion of “device Data” message includes device “Status byte”. This information is sent every time
regardless if there are any alarms or not. It mostly describes communication quality between Host and the
Controller.
Table 13 Status Byte
bit Condition Set Clear
7 No Weigands from device 1 minute with no Weigands Weigand comm. OK
6 Attached device not connected Weigand lines low Weigand lines high
5 Problems communicating to Host Errors during receiving on 485 “Ack” received
4 Last message was out of order Messages not in sequence “Ack” received
3 Lost Weigand message Weigand parity check failed “Ack” received
2 Buffer overflow Lost message due to too many
Weigands since last pool
“Ack” received
1 Designated monitor “Start Monitoring” message “Stop Monitoring” message
0 = 0, To prevent ‘01’ or ‘1B’ Never Always
When TIC or TIF alarm needs to be sent, it is added after the Status byte. The Weigand message received
from the Controller is stripped of parity bits and the rest of the message is shifted to the right for one bit .
The result is four byte field as shown in the Figure 11 First figure shows Weigand message as received
from the Controller, and second one shows same message ready to be appended to the “Device Data”
message.. First two bits are always ‘0’.