Figure 1: Modbus Rs485 Connections - Sensor Electronics SEC Millenium Series Instruction And Operation Manual

Figure 1: Modbus RS485 Connections

S1
P5
S2
First Time Configuration
When SEC 3120 units are first removed from the shipping container, unless
otherwise instructed upon ordering, units may arrive configured in the following modes:
1. Sensor Role: Unique- Multiple sensors can be connected having different gas
types, units of measure and ranges. This can be changed to "Identical" mode if
all attached sensors have identical gas types, ranges and units of measure, thus
allowing redundancy of measurement. It can also be changed to "Single" mode,
where only one sensor is attached to the unit in the sensor 1 connector. In "Single"
mode, the unit will ignore anything connected to the sensor 2 connector.
2. Relay Mode: OR- Sensors control the alarm relay coils in a logical "OR" fashion.
Fault relay is always controlled in a logical "OR" fashion (Any sensor fault drives
fault relay coil). The alarm relay logic mode can be changed to "AND"- forcing
both sensor's alarm status to be in agreement before the alarm relay coils are
driven (except for fault relay coil). This mode is typically used with the
"Identical" Sensor Role to provide measurement redundancy.
3. Modbus Network ID Mode: Unique- One Network ID is assigned to each
sensor, typically sensor 2 ID is greater than sensor 1 ID. These ID's can be
independently adjusted and are available on the bus and the unit will respond to
either ID for all sensors attached (Ex: Sensor 2 ID: 12, Sensor 1 ID 11). This can
be changed to "Single" mode, where all sensors are accessed through a single ID
and the IDs are identical to all sensors (Sensors 1 and 2 IDs are 5).
4. RS485 Bus Settings: SEC Default- Baud rate is 9600, stop bits are 2, parity is set
to none. This can be changed to "Alternate:"- Baud rate 9600, stop bits 1, parity
none. The bus settings may also be set to custom values, where the baud rate, stop
bits and parity are independently changed (i.e. Baud rate 19200, stop bits 1, parity
odd).
SEC 3120 16-bit Modbus Manual
For Version 1.2 and above
1
2
P5
3
RS485 A
4
RS485 B
5
Page 7 Of 46
December 2012
5
RX-
4
3
RX+
2
1
Gateway
Sensor Electronics Corporation
P/N 1580282, Rev. 1, 20121228