Quatech RS-422/485, MPA-200/300 user manual Circuit CD DTE Ready DTR Connector Notation +DTR,-DTR

CIRCUIT CD - DTE READY (DTR)

￿CONNECTOR NOTATION: +DTR,-DTR

￿DIRECTION: To DCE

This signal controls the switching of the DCE to the communication channel. The DTE will generate this signal to prepare the DCE to be connected to or removed from the communication channel.

CIRCUIT LL - LOCAL LOOPBACK (LL)

￿CONNECTOR NOTATION: LLBK

￿DIRECTION: To DCE

This signal provides a means whereby a DTE may check the functioning of the DTE/DCE interface and the transmit and receive sections of the local DCE.

Note:

The local loopback and remote loopback signals are optional and are omitted from the DCE configuration of the MPA-200. Since testing will never occur for this configuration, the test mode signal will always be in the OFF condition for the DCE. These three test signals follow the EIA-423-A standard while the remaining signals follow the EIA-422-A standard.

CIRCUIT RL - REMOTE LOOPBACK (RL)

￿CONNECTOR NOTATION: RLBK

￿DIRECTION: To DCE

This signal provides a means whereby a DTE or a facility test center may check the transmission path up to and through the remote DCE to the DTE interface and the similar return transmission path.

35 Quatech Inc., MPA-200/300 Manual