FloBoss 407 Instruction Manual
Rev 5/00 4-3
Table 4-1. Communications Cards LED Indicators
LEDs STATUS AND ACTIVITY
RXD The RXD receive data LED blinks when data is being received. The LED is on
for a space and off for a mark.
TXD The TXD transmit data LED blinks when data is being transmitted. The LED is
on for a space and off for a mark.
DTR The DTR data terminal ready LED lights when the modem is ready to answer an
incoming call. When DTR goes off, a connected modem disconnects.
DCD
The DCD data carrier detect LED lights when a valid carrier tone is detected.
CTS CTS indicates a clear to send message.
RTS The RTS ready to send LED lights when the modem is ready to transmit.
RI The RI is the ring indicator LED light.
DSR The DSR is the data set ready indicator LED light.
OH The OH is the off hook indicator LED light. A dial tone has been detected and the
telephone line is in use by your modem.
NOTE: The last three LED indicators are used only on the dial-up modem communication card.
4.2.2 EIA-422/485 Serial Communications Card
The EIA-422/485 communication cards (see Figure 4-2) meet EIA-422/485 specifications for
differential, asynchronous transmission of data over distances of up to 4000 feet. The EIA-422 drivers
are designed for party-line applications where one driver is connected to, and transmits on, a bus with
up to 10 receivers. The EIA-485 drivers are designed for true multi-point applications with up to 32
drivers and 32 receivers on a single bus.
NOTE
EIA-422 devices should not be used in a true multi-point application where multiple
drivers and receivers are connected to a single bus and any one of them can
transmit or receive data.
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