XT09-PKI-E-NA Digi International/Maxstream, XT09-PKI-E-NA Datasheet - Page 19

• Manufacturer Part Number: XT09-PKI-E-NA
• Description: MODEM RF 900MHZ 1W ETHER INT
• Manufacturer: Digi International/Maxstream
• Series: XTend™r

Specifications of XT09-PKI-E-NA

• Function: Transceiver, Modem
• Modulation Or Protocol: FHSS, FSK
• Frequency: 900MHz
• Interface: RJ-45 Ethernet
• Sensitivity: -110dBm
• Data Rate - Maximum: 10 kbps
• Voltage - Supply: 7 V ~ 28 V
• Package / Case: Module
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Power - Output: -
• Applications: -

9XTend‐PKG‐E™ Ethernet RF Modem – Product Manual v2.x4x [2007.01.04]
Binary Command Mode
Sending and receiving parameter values using binary commands is the fastest way to change
operating parameters of the modem. Binary commands are used most often to sample signal
strength [refer to DB (Received Signal Strength) parameter] and/or error counts; or to change
modem addresses and channels for polling systems when a quick response is necessary. Since the
sending and receiving of parameter values takes place through the same serial data path as 'live'
data (received RF payload), interference between the two types of data can be a concern.
Common questions about using binary commands:
The CMD pin (GPI1) must be asserted in order to send binary commands to the modem. The CMD
pin can be asserted to recognize binary commands anytime during the transmission or reception
of data. The status of the CMD signal is only checked at the end of the stop bit as the byte is
shifted into the serial port. The application does not allow control over when data is received,
except by waiting for dead time between bursts of communication.
If the command is sent in the middle of a stream of payload data to be transmitted, the command
will essentially be executed in the order it is received. If the modem is continuously receiving data,
the radio will wait for a break in the received data before executing the command. The CTS signal
will frame the response coming from the binary command request [refer to figure below].
A minimum time delay of 100 µs (after the stop bit of the command byte has been sent) must be
observed before the CMD pin can be de-asserted. The command executes after all parameters
associated with the command have been sent. If all parameters are not received within 0.5 sec-
onds, the modem returns to Idle Mode.
Note: When parameters are sent, they are two bytes long with the least significant byte sent first.
Binary commands that return one parameter byte must be written with two parameter bytes.
Commands can be queried for their current value by sending the command logically ORed (bit-
wise) with the value 0x80 (hexadecimal) with CMD asserted. When the binary value is sent (with
no parameters), the current value of the command parameter is sent back through the DO pin.
Figure 3‐06. Binary Command Write then Read
Signal #4 is CMD
Signal #1 is the DI signal
Signal #2 is the DO signal from the radio
Signal #3 is CTS
In this graph, a value was written to a reg-
ister and then read out to verify it. While
not in the middle of other received data,
note that the CTS signal outlines the data
response out of the modem.
IMPORTANT: In order for the modem to recognize a binary command, the RT (GPI1 Configuration)
parameter must be set to one. If binary programming is not enabled (RT parameter value is not equal
to ‘1’), the modem will not recognize that the CMD pin is asserted and therefore will not recognize the
data as binary commands.
Refer to [p21] for a binary programming example (DT command example returns two bytes).
© 2007 MaxStream, Inc., Confidential & Proprietary ‐ All Rights Reserved
• What are the implications of asserting CMD while live data is being sent or received?
• After sending serial data, is there a minimum time delay before CMD can be asserted?
• Is a time delay required after CMD is de-asserted before payload data can be sent?
• How does one discern between live data and data received in response to a command?
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