IBUC Operation Manual 6-5
Terrasat Communications, Inc.
Rev. A
in ASCII mode are shown in the command set, Table 6.9. Commands and values
available in Legacy mode are shown in item 4) RS-485, pages 6-6 through 6-10.
FSK and RS-485 are tied together by the Mode of operation (Legacy-binary or
ASCII). Once the mode is selected, both will work in the same mode. FSK link
specifications are as follows:
Transmitter
Frequency 650 KHz +/-5%
FSK deviation +/- 60 KHz Nominal (+60 KHz mark)
Deviation tolerance +/- 50 KHz minimum ; +/-70 KHz maximum
Output Level -5 to –15 dBm
Output impedance 50 OHM
Start Tone 710 KHz
Start Tone time 10 ms
Receiver
Locking range +/- 32.5 KHz
Input impedance 50 OHM
Input Sensitivity -15 dBm
For FSK operating in Legacy Binary the data will be transmitted at 9600 bit/s with 8 data
bits, no parity, and one stop bit.
In order to maintain synchronization, the RS485 receiver will reset if a message is not
completed within 50 ms of initiation.
The IBUC is capable of responding to messages at rate of one every 20 ms.
4) RS485 two wire half-duplex which is on a separate cable. There are two modes of
operation for RS-485 interface: ASCII mode and Legacy-binary mode.
RS-485 in ASCII mode:
The RS-485 interface is a standard 2-wire interface (DATA+, DATA-). The baud rate is
programmable to 1200, 2400, 4800, 9600, 19200, 38400, 57600 or 115200 Baud. The
data is transmitted asynchronously as 8 bits, no parity, and 1 stop bit.
Basic protocol:
Start of Packet: < (ASCII code 60; 1 character)
Target Address: (4 characters)
Address De-limiter: / (ASCII code 47; 1 character)
Instruction code: (3 characters)
Code qualifier: = or ? (ASCII code 61 or 63; 1 character)
Optional arguments: (n characters)
End of Packet: Carriage Return (ASCII code 13; 1 character)
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