TM 11-6625-3145-14
Theory of Operation-318/338 Service
RS-232 CONTROL <18>
The RS-232 control circuit consists of the baud-rate selector, level converter, and serial I/O controller. This circuit provides
the remote control operation. A simplified diagram of this stage is shown in Figure 4-11.
Baud-Rate Selector. The baud-rate selector circuit consists of a programmable bit-rate generator (A07U5), and a data
latch (A07U45).
Programmable bit-rate generator A07U5 supplies the receive and transmit clock signals to SIO PORT-B. This clock rate is
determined by the logic inputs on A07U5 pins 11, 12, 13, and 14 (S3 through S0, respectively).
The output positive-going edge at pin #13 of I/O selector A07U30 latches data at A07U45. This latched data (D7, D6, D5,
and D4) is supplied to the S3 through S0 inputs of A07U5.
The input clock rate for A07U5 is the same as for A07U6; 19.2K baud and external clock for RS-232 are not used. (Refer
to Table 4-10.)
Level Converter. The level converter stage consists of the RS-232 transmitter A07U41 and the RS-232 receiver A07U40.
Transmitter A07U41 converts TTL-level signals to RS-232 level, and receiver A07U40 converts RS-232 level signals to
TTL level.
RS-232 transmit signals (TXD, RTS, DTR) are controlled by SIO PORT-B. Receive signals (RXD, CTS, DSR, CD) are
controlled by the external device.
The DRS signal status appears at pin 11 of A07U32.
Serial I/O Controller. Refer to the Serial Acquisition section.
Table 4-10.
PROGRAMMABLE BIT-RATE GENERATOR OUTPUTS
S3
S2
S1
S0
Output Rate
L
L
L
L
EXTERNAL CLOCK
L
L
L
H
19.2K baud
L
L
H
L
50 baud
L
L
H
H
75 baud
L
H
L
L
134.5 baud
L
H
L
H
200 baud
L
H
H
L
600 baud
L
H
H
H
2400 baud
H
L
L
L
9600 baud
H
L
L
H
4800 baud
H
L
H
L
1800 baud
H
L
H
H
1200 baud
H
H
L
L
2400 baud
H
H
L
H
300 baud
H
H
H
L
150 baud
H
H
H
H
110 baud
Input SERIAL-CLOCK is 2.4576 MHZ.
4-34
Summary of Contents for 318
Page 119: ...318 VERIFICATION AND ADJUSTMENT PROCEDURES ...
Page 182: ...338 VERIFICATION AND ADJUSTMENT PROCEDURES ...
Page 253: ...318 ___________________ TROUBLESHOOTING TREES ...
Page 344: ...338 TROUBLESHOOTING TREES ...
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Page 518: ...TM 11 6625 3145 14 318 338 4434 924 338 Block Diagram ...
Page 519: ...TM 11 6625 3145 14 318 338 4434 925 318 Acquisition Module Wiring Diagram ...
Page 520: ...TM 11 6625 3145 14 318 338 4434 926 318 338 Mainframe Wiring Diagram ...
Page 521: ...TM 11 6625 3145 14 318 338 4434 926 338 Acquisition Module Wiring Diagram ...
Page 522: ...TM 11 6625 3145 14 318 338 4434 928 Figure 9 1 318 A01 Input A Board Component Locations ...
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Page 544: ...TM 11 6625 3145 14 Figure 9 9 318 338 A11 Inverter Board component Locations ...
Page 546: ...TM 11 6625 3145 14 Figure 9 10 318 338 A12 Regulator Board Component Locations ...
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Page 553: ...TM 11 6625 3145 14 318 338 SERVICE ...
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