MSK Modem
8
MX809
C-BUS allocations for the MX809 are shown in Table 5 and Table 6.
Command Assignment
HEX
General Reset
Write to Control Register
Read Status Register
Read RX Data Buffer
Write to TX Data Buffer
Write to SYNC Program
01
48
49
4A
4B
4C
Address/Command
Binary
MSB
LSB
Command Data
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
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
H
to 44
H
(Table 5) and
transactions with Modem 2 will use 48
H
to 4C
H
(Table 6).
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”).
1998
MX-COM, Inc.
www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054
Doc. # 20480036.004
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
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