Micom P631 Technical Manual Download

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either by a special fiber-optic connector or an RS 485 interface with twisted pair
copper wires. Communication interface 2 is only available as an RS 485 interface.
The selection and assembly of a properly cut fiber-optic connecting cable
requires special knowledge and expertise and is therefore not covered in this
operating manual.

Warning!

⚫

The fiber-optic interface may only be connected or disconnected when the
supply voltage for the device is shut off.

An RS 485 data transmission link between a master and several slave devices
can be established by using the optional communication interface. The
communication master could be, for instance, a central control station. Devices
linked to the communication master, e.g. P631, are set-up as slave devices.
The RS 485 interface available on the P631 was designed so that data transfer in
a full duplex transmission mode is possible using a 4-wire data link between
devices. Data transfer between devices using the RS 485 interface is set up only
for a half duplex transmission mode. To connect the RS 485 communication
interface the following must be observed:

●

Only twisted pair shielded cables must be used, that are common in
telecommunication installations.

●

At least one symmetrical twisted pair of wires is necessary.

●

Conductor insulation and shielding must only be removed from the core in
the immediate vicinity of the terminal strips and connected according to
national standards.

●

All shielding must be connected to an effective protective ground surface at
both ends.

●

Unused conductors must all be grounded at one end.

A 4

‑

wire data link as an alternative to a 2-wire communications link is also

possible. A cable with two symmetrical twisted pair wires is required for a 4-wire
data link. A 2-wire data link is shown in

Fig. 5-11, (p. 5-16)

, and a 4-wire data

link is shown in

Fig. 5-12, (p. 5-17)

as an example for channel 2 on the

communication module. The same is valid if channel 1 on the communication
module is available as a RS 485 interface.
2-wire data link:
The transmitter must be bridged with the receiver on all devices equipped
electrically with a full duplex communication interface, e.g. the P631. The two
devices situated at either far end must have a 200 to 220

resistor installed to

terminate the data transmission conductor. In MiCOM Px3x devices, and also in
the P631, a 220

resistor is integrated into the RS 485 interface hardware and

can be connected with a wire jumper. An external resistor is therefore not
necessary.
4-wire data link:
Transmitter and receiver must be bridged in the device situated on one far end
of the data transmission conductor. The receivers of slave devices, that have an
electrically full-duplex communication interface as part of their electrical system,
e.g. the P631, are connected to the transmitter of the communication master
device, and the transmitters of slave devices are connected to the receiver of the
master device. Devices equipped electrically with only a half duplex RS 485
communication interface are connected to the transmitter of the communication
master device. The last device in line (master or slave device) on the data
transmission conductor must have the transmitter and receiver terminated with
a 200 to 220

Micom P631, Technical Manual

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