Chapter 7 Commands
TransCore Proprietary
7–87
Note:
The Encompass 4 Reader transmits ID codes to the host computer when the Encompass
4 Reader is in data mode. If the Encompass 4 Reader remains in the command mode with tags
passing through the read zone, all tag IDs are not reported.
Command Mode
While the Encompass 4 Reader is in the command mode, the host computer sends commands to the
Encompass 4 Reader that can be used to control the operation and configuration of the reader. After the
Encompass 4 Reader receives a command, it transmits a command response message. Typically, the
command message contains
Error, Done
, or data relating specifically to the command request. These
messages may be of variable length since some commands require information as part of the message;
for example,
Display Wiegand Mode Status
.
Communications can be lost if the host computer attempts to send certain commands under marginal
communications conditions. For example, if the host computer transmits the command request to change
the baud rate and the Encompass 4 Reader properly receives the request and transmits the
Done
message, one of the two following conditions may occur:
•
If the host computer receives the
Done
message, then both the host and the Encompass 4
Reader switch to the new baud rate, and communications are maintained.
Note:
In many applications, the host must be set to the new baud rate as it will not change
automatically. The Encompass 4 Reader changes the baud rate immediately after issuing the
Done
message.
•
However, if the host does not receive the
Done
message transmitted by the Encompass 4 Reader,
the host assumes that the command was not properly sent and does not switch to the new baud
rate, causing a loss of communications.
Caution
The host computer should not attempt to change communications parameters or protocols
during marginal communications conditions, otherwise a loss of communications can result.
Download Mode
In download mode, the Encompass 4 Reader allows the host to download new software.
While in download mode, the reader communications port parameters are fixed at the following factory-
default settings: 38400 baud, 8 data bits, 1 stop bit, no parity, software flow control (XON/XOFF), basic
protocol.
While in download mode, the Encompass 4 Reader turns RF off, does not process tags, and does not echo
host commands.
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