Communications
49
10 Communications
10.1
Overview
This chapter provides additional information about remote com-
munications connections, programming, and general operation.
The SB Energy-Comm trip unit is equipped with communica-
tions ports that allow it to be integrated in energy monitoring
networks. The serial (EIA-232) port on the front of the device
allows a PC or laptop to download device settings and request
information in much the same way as an ACCESS supervisory
device. Five different data transfer rates are available, inde-
pendent of the transfer rate setting for the EIA-485 port.
The SB Energy-Comm trip unit is fully compatible with Siemens
supervisory software that can display all measured parameters
and status information, waveform data, and data logs provided
by the trip unit. The supervisory software can also be used to
program all the setup parameters remotely.
The open communications protocol of the SB Energy-Comm
trip unit allows access to all data and setup parameters by
third-party systems. Refer to the
SB Energy-Comm Trip Unit
SEAbus Protocol Reference Manual
(Bulletin IPIM-2209A) for
a complete discussion of the protocol and device-specific
packets for the SB Energy-Comm trip unit. Refer to the appen-
dix,
SEAbus Plus Packet,
for a general discussion of SEAbus
packets. Contact your local Siemens sales office for informa-
tion on network gateways to other network protocols.
10.2
Viewing Communications Settings
To view and change communications settings, select
Communi-
cations
from the
Main Menu
. The following screen appears:
The first option in the
Communications Menu
displays the
present configuration of the communications settings. Select
View Comm Config
, and the following screen appears:
10.3
PC Communication
EIA-232 is commonly used for short distance, point-to-point
communications. The distance between a host computer (or
PLC) and a single remote device must be less than 50 feet in
length for hard-wired connections. Connection using modems
via dedicated or dial-up telephone lines is also possible.
Siemens SBWin Software is used to optionally configure trip
unit settings via a laptop PC using the serial port on the front of
the trip unit.
To configure the EIA-232 serial port baud rate, select
RS232
Baud Rate
from the
Communications Menu
. The following
screen appears:
Press the Up
or Down
Arrow keys to adjust the baud rate
to match that of your computer, PLC or modem. Then press
Escape
to set the rate, followed by Enter
.
The EIA-232 port RTS line is operational and must be used if
required by any hardware device connected to the SB Energy-
Comm trip unit.
10.4
ACCESS Communication
ACCESS is a master/slave communications scheme devel-
oped by Siemens Energy & Automation. Based on a serial,
two-wire EIA-485 network, ACCESS allows a single master
device to communicate with many Siemens field (slave)
devices. In addition to real-time data, almost all functions and
information available locally at the device interface (pushbut-
tons, diagnostic LEDs, etc.) are accessible by the master from
its remote location. Up to 32 slave devices can be connected
in a single EIA-485 network, with a maximum of four parallel
485 loops connected to a single master unit.
Communication methods between the remote EIA-485 site and
the master computer station can include a direct EIA-485 con-
nection, limited to 4000 feet (approximately 1200 meters), tele-
phone lines with modems, fiber-optic and/or radio links. An
EIA-232 to EIA-485 converter, such as the Siemens Isolated
Multi-Drop Converter, is required between the EIA-232 port of
the computer or modem and the EIA-485 network. The RS-485
port is connected via the breaker’s secondary terminals.
The master, or ACCESS host, is typically a PC running supervi-
sory software. Siemens field devices supporting ACCESS com-
munications include the 4300, 4700, and 4720 power meters,
various protective relays, the SAMMS motor controller, and
Sensitrip, SB, and Static Trip III trip units.
Figure 10.1
illustrates
a typical ACCESS system.
