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System Monitor
80175-01
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PROTOCOL SPECIFICATIONS
MODEM CONTROLS
The following definitions apply to the RS-232C signals as implemented by the Serial Interface. The
modem control signals DTR, DSR, DCD, RTS and CTS are active only if the MDEM switch (SW2)
on the Serial Interface circuit board is set ON.
Note
A RS-232C ON condition is a binary state of 0 and has a positive voltage level on the
interface. A RS-232C OFF condition is a binary state of 1 and has a negative voltage level
on the interface.
RTS - REQUEST TO SEND
Continually asserted ON.
DTR - D A T A TERMINAL READY
Asserted ON unless DCD is OFF for greater than 10 seconds. Then DTR is placed OFF
until DSR is set OFF. Once DSR is OFF, DTR is set ON.
TXD - TRANSMITTED DATA
When not transmitting, TXD is in OFF state
CTS - C L E A R TO SEND
Received from modem. If Modem controls are on (MDEM ON), this signal must be ON
to enable message transfers. Loss of CTS does not turn DTR OFF.
DCD - D ATA CARRIER DETECT
Received from modem. I f DCD is OFF, message transfers will be disabled to/from
interface. Loss of DCD for 10 seconds causes DTR to be turned OFF.
DSR - D ATA SET READY
Received from modem. DSR should be set OFF at modem when DTR is set OFF at Serial
Interface. When DSR is set OFF, DTR will be set ON. Then the modem should set DSR
ON completing the handshake.
RXD - RECEIVED DATA
Data received from modem.
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Содержание 3300/01 Series
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