Alstom MiCOM P846, Technical Manual

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Getting Started P846/EN GS/D
MiCOM P846 (GS) 3-13
d
GS
Figure 6: Front port connection
The relay is Equipment (DCE) device. Thus the pin connections of
ransmit data
mon
one r pins are connecte y should be connected to the
Way 9 Way
Rx Receive data
mon
or su ta communi ion, t ust be connected to the Rx pin
a Data Communication
the relay’s 9-pin front port are as follows:
Pin no. 2 Tx T
Pin no. 3 Rx Receive data
Pin no. 5 0V Zero volts com
N of the othe d in the relay. The rela
serial port of a PC, usually called COM1 or COM2. PCs are normally Data Terminal
Equipment (DTE) devices which have a serial port pin connection as below (if in doubt check
your PC manual):
25
Pin no. 2 3 2
Pin no. 3 2 3 Tx Transmit data
Pin no. 5 7 5 0V Zero volts com
F ccessful da cat he Tx pin on the relay m
on the PC, and the Rx pin on the relay must be connected to the Tx pin on the PC, as shown
in Figure 7. Therefore, providing that the PC is a DTE with pin connections as given above,
a ‘straight through’ serial connector is required, i.e. one that connects pin 2 to pin 2, pin 3 to
pin 3, and pin 5 to pin 5. Note that a common cause of difficulty with serial data
communication is connecting Tx to Tx and Rx to Rx. This could happen if a ‘cross-over’
serial connector is used, i.e. one that connects pin 2 to pin 3, and pin 3 to pin 2, or if the PC
has the same pin configuration as the relay.