User's Manual

QTI Page 7 of 15 Revision: D
Form #: 30Z0250 Effective Date: 1 August 2010
NOTE: Elevating an antenna will increase transmission and/or reception range significantly. The use
of relays/repeaters can also be used to increase transmission ranges. Also transmitting and receiving
antennas should both point in the same direction (typically up) so they have the same polarization.
Section 3: Serial Interface
The MCDT defaults to a low-power shut down mode with the receiver still operating (if installed). If
push is enabled (“PSH 1”), the MCDT will send the message via the serial port upon receiving an RF
message, and then return to shut-down immediately. The user may initiate serial communication by
sending the MCDT two carriage returns. This is to allow the MCDT time to wake-up from the power-
down mode. After 1 minute of inactivity on the serial port, the MCDT returns to low-power shut down
mode. If the user has disabled the PUSH setting (“PSH 0”), and a new message is received, the MCDT
will send its RS485 ID. See the SID command. This is used to wake-up the user’s application
processor. Once awake the user can poll to get the new message. See the NEW command. If the
MCDT is still awake and the MCDT receives a new message, the shut-down mode will not occur until
the RS485 serial ID has been sent and acknowledged. The user’s application must respond or an
infinite loop condition would occur causing the MCDT to never shut-down.
The MCDT communicates over RS-485. Commands must be followed by a carriage return (<CR>).
Settings are retained only until power is turned off unless the SAV command is used to store them to
the unit’s flash memory. When sending commands and queries, a two-digit hexadecimal checksum
(cs) can be used to check data integrity, refer to Checksum section after command list.
SETTINGS
38400 baud [fixed], No parity, 8 bit, 1 stop bit, No flow control
Message Serial Format
Decoded message is sent via RS-485:
RXM XX YYY ZZ R<CR> - Received message
TXM XX YYY ZZ<CR> - Transmitted message
XX = Message Type, YYY = ID code, and ZZ = status code; XX and ZZ are hexadecimal, and YYY is
decimal. R is the receive signal strength indicator, see RSS command.
Example: TXM 0D 244 0B
Message sent by user – Transmits message type “EMIDS” with an ID code of 244 and a status code of
TEST, FAULT.
MESSAGE TYPE (XX)
The message type consists of two (2) hexadecimal characters. The first character shows the parity; the
most significant bit will be set if the parity is bad. The second character identifies the type.