ABB ProtectIT REL 551 2.5 Installation And Commissioning Manual page 76

Configure the interface modules for V.36,
X.21 and RS530
Designation Explanation
RXD Received data
SCREEN Connection of cable screen
TCLK DCE Transmitter signal timing from DCE
TCLK DTE Transmitter signal timing from DTE
TXD Transmitter data
For the co-directional operation the transmission rate of the transmitted signal must be set.This
setting, 56 or 64 kbit/s, is done on the HMI under:
Configuration/TerminalCom/RemTermCom/BitRate
For X.21 and contra-directional operation no settings are available.
For the signals used by the protection, the communication module for V.36 also fulfils the older
recommendation for V.35.
Chapter 8
Configuring the 56/64 kbit data
communication modules
67