Siemens ISOLATED MULTI-DROP SG-6048-01 - Manual (Page 5)

2
Setting Up the Converter
2 Siemens Energy & Automation, Inc.
2 Setting Up the Converter
2.1 Overview
Before connecting the converter to your system, understand
the connectors, LEDs and switches. This section describes
each of the following features according to their functions:
• four RS-485 communications ports
• one RS-232 communications port
• power module
• three configuration switches for communications
• manual and automatic operating modes
2.2 RS-485 Communications Ports
The Isolated Multi-Drop converter is equipped with four
RS-485 ports located on the converter’s front panel,
as illustrated in Figure 2.1
Figure 2.1 Connectors on Front Panel
Each port allows you to connect as many as 32 field devices
on a single RS-485 communications cable; however, your
application software may limit the number of devices your
system can accommodate. Each port has Data(+) and
Data(-) terminals and a ground terminal for the cable shield.
For diagnostics, each port is equipped with a yellow
transmit (Tx) LED and a green receive (Rx) LED, located on
top of the device. The Tx LEDs blink during the transmission
of data, which occurs on all ports simultaneously; only one
Rx LED blinks when data is received. The LEDs are
illustrated in Figure 2.2
Figure 2.2 Communications LEDs on the Top Panel
+
_
RS485 RS485 RS485
RS-485 receptacles
RS485
+
_
+ _ +
_
2.3 RS-232 Communications Port
The converter is equipped with one RS-232
communications port located on the rear panel, as
illustrated in Figure 2.4. This port lets you connect the
converter to a PC for desktop operation, or to a short-haul
or dial-up modem for remote operation.
2.4 Power Module
The interface of the converter’s power module is located on
the rear panel, as illustrated in Figure 2.4. The power
module includes an ON/OFF switch, an indicating power
(PWR) LED, a 120 VAC power input, and a 15 VDC power
output. The 15 VDC output is used to provide power to
Static Trip III
TM trip units and SAMMS TM motor control and
protection relays during testing. The filtered input next to the
power switch is for providing line power to the converter.
The power switch turns the converter on and off, and the
PWR LED illuminates when the converter is turned on.
2.5 Configuration Switches
On the rear panel are the converter’s three configuration
switches, collectively labeled “TX CONTROL”. Set these
switches before operating the converter. Refer to Figure 2.4
for the location of these switches. The two switches, labeled
DCD/RTS and MAN/AUTO, and one thumbwheel switch,
labeled BAUD are described below. This section describes
the uses of each configuration switch in more detail.
2.5.1 TX CONTROL Switches
The MAN/AUTO switch places the Isolated Multi-Drop
converter in either manual or automatic operating mode,
both of which are described below. Your application
software determines which mode you should use.
The DCD/RTS switch is set according to the method of data
transmission for your configuration. Set the switch to DCD
for the Data Carrier Detect (DCD) circuit (pin 8, RS-232
cable) to send a message to the PC when a proper carrier
signal is received. Set the switch to RTS for the Request To
Send (RTS) circuit (pin 4, RS-232 cable) to send a message
to the converter requesting permission to send data on the
Tx Data circuit (pin 2, RS-232 cable). Figure 2.3 shows the
switches set to DCD and AUTO.
Figure 2.3 Tx Control Switches