Black Box ME801-C, Руководство пользователя

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SHORT-HAUL MODEM-B SYNC (SHM-B SYNC)
Here is how the SHM-B Sync implements flow control:
As soon as the system begins operating, each SHM-B
Sync unit forces its own RTS, CTS, DSR (Data Set
Ready), and DTR (Data Terminal Ready) signals “high”
(above +3V), and as soon as each unit detects the
presence of the one at the far end, it also raises CD
(Carrier Detect) in order to signal the attached device
to expect data. If the cables are correctly wired and
attached, the system is ready for continuous data
transmission.
The control signals will stay in this state unless:
• One of the SHM-B Sync units is powered down
(all signal transmission at its end will cease and
the other SHM-B Sync will lower CD);
• The 4-wire cable is broken or detached (both
SHM-B Sync units will lower CD);
• An attached device is powered down or lowers DTR
or RTS (its attached SHM-B Sync unit will drop
carrier and the other unit will lower CD).