Table 4 Status Response Message Fields
Field
Description
Hex
ASCII
Start of Message
These two bytes, along with the Message Type
byte, designate the start of the data message.
7E7E
~~
Message Type
An
02H
indicates that this message is a status
response.
02
STX
Transponder Seen
Count
The Transponder Seen Count is a single byte,
hexadecimal field. At power-up, the interrogator
initializes this Seen Count byte to 00. This value
is incremented each time a tag with a unique ID
moves out of the RF field, then back into the RF
field. This field is useful in determining whether
a train has multiple tag reads of a given ID due
to a change in the train’s direction.
00 - FF
N/A
Number of Messages
from Host with Bad
CRCs
At power-up, the interrogator initializes this
byte with 00. It is incremented each time a
message with a bad CRC is received from the
Host.
00 - FF
N/A
Number of incomplete
Host Messages
At power-up, the interrogator initializes this
byte with 00. It is incremented each time an
incomplete message is received from the
Host.
00 - FF
N/A
Reserved
Reserved
0
NUL
Reserved
Reserved
0
NUL
Reserved
Reserved
0
NUL
Cyclical Redundancy
Check
This field is a single byte (8-bits) cyclical
redundancy check (CRC). Includes the Start of
Message, Message Type, Transponder Seen
Count, Number of Messages from Host with
bad CRCs, and Number of Incomplete Host
Messages. Refer to
for a description of the CRC algorithm.
There is no carriage return or line feed for this
message.
00 - FF
N/A
Retransmit Request
Note: The Retransmit Request should only be used when the train is stationary. Sending this
command simultaneous to tags being read can create a condition whereby the interrogator will no
longer report tags until power cycled.
The Retransmit Request Command tells the transponder to retransmit the last tag ID. (
BB
must be entered
in upper case).
AI1422E Reader User Guide
TransCore Proprietary
6–24
