CHAPTER THREE
A. PACKED BCD FORMAT:
Outputs a string of eight bit characters, each of which contains two BCD digits. Normal
ASCII control characters cannot be used with this format, since data values can take on
the image of control characters.
B. ASCII FORMAT:
Outputs a string of ASCII numeric characters, each character representing one digit of the
time message.
3.11.2 PROGRAMMING
If the handshake lines (DTE/DTR and RTS/CTS) are used, then any baud rate up to the
maximum 38400 can be used without concern. However, if these handshake lines are not used,
then a delay of up to 10 milliseconds may be required between the end of one character and the
beginning of the next character in the command string being input to the TM7000. This time
delay ensures that the command decoder has serviced the previous character and is ready for the
next one.
A command string to the TM7000 is a string of six ASCII characters, which always begins with
two "slash" characters (//). The sixth character is often followed by a data character, as in the
case of setting the time of the generator.
3.11.3 TO ENTER SETUP AND CONTROL DATA
a. The computer (DTE) initiates the handshake by asserting DTR. The TM7000
responds by asserting DSR.
b. The computer then asserts RTS. The TM7000 responds by asserting CTS.
c. The computer outputs the first character of the command string.
d. When the character is received, the TM7000 removes CTS until the character has
been processed. When the TM7000 is ready for the next character, it will assert
CTS.
e. Steps “c” and “d” are repeated as often as is necessary to transmit a complete
command (plus a data character when appropriate).
f. After all command characters have been transferred, the computer may remove
both RTS and DTR until a new command is to be sent. Alternatively, the
computer may remove RTS, but continue to assert DTR in anticipation of a later
command transmission.
3-28 TM7000 TymMachine TCG/T (Rev D) Symmetricom, Inc.
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