MSK Modem
8
MX809
C-BUS allocations for the MX809 are shown in Table 5 and Table 6.
Command Assignment
Address/Command
Binary
Command Data
HEX
01
MSB
LSB
General Reset
00000001
01001000
01001001
01001010
01001011
01001100
Control Register bits set to logic “0”
1 byte instruction to Control Register
1 byte reply from Status Register
1 byte of data from RX Data Buffer
1 byte of data to TX Data Buffer
Write to Control Register
Read Status Register
Read RX Data Buffer
Write to TX Data Buffer
Write to SYNC Program
48
+
+
+
+
+
49
4A
4B
4C
2 bytes of SYNC Word to SYNC
Program Register
Table 6: Modem No. 2 C-BUS Address/Commands – (Address Select input at a logic “1”)
5.2 Address Select
This input allows 2 MSK Modems on the same BUS, using the correct addressing.
When operating in a system using 2 MSK Modems, one MSK Modem is designated No. 1 and requires its
Address Select input to be held at a logic “0”. The second Modem (No. 2) requires its Address select input to
be held at logic “1”.
All C-BUS transactions with Modem 1 will use Address/Command allocations 40 to 44 (Table 5) and
H
H
transactions with Modem 2 will use 48 to 4C (Table 6).
H
H
For explanation purposes, further descriptions of MX809 MSK Modem internal register functions will deal
primarily with MSK Modem No. 1 (Address Select at logic “0”).
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