ACOEM Met One Instruments GAS-1060, User Manual

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Communications Page 61
4. Communications
The Serinus has a number of different interfaces for communication with other equipment (RS232,
USB, 25 pin digital/analog input/output, TCP/IP network (optional) and Bluetooth). A demonstration
version of Ecotech’s Airodis software is included with the instrument, enabling basic data downloads
and remote operation from a PC running MS Windows (7 or 8). The full version of Airodis is available
separately and includes automated collection, data validation and complex reporting by multiple
users. Please refer to the Airodis Manual and Section 4.6 for details on setting up and communicating
with the Serinus.
Figure 10 – Communication Ports
4.1 RS232 Communication
RS232 communication is a very reliable way to access data from the instrument and is recommended
for use in connection to a data logger for 24/7 communication. Both RS232 ports are configured as
DCE and can be connected to DTE (Data Terminal Equipment such as a data logger or computer).
Port #2 also supports a multidrop arrangement (a configuration of multiple instruments connected
via the same RS232 cable where the transmit signal is only asserted by the instrument that is spoken
to).
For reliable multidrop RS232 communications please follow these guidelines:

Verify that the Serial ID is set to a unique value which is different to the other instruments in the
chain (refer to Section 3.4.23).

All of the instruments in the multidrop chain must have the same baud rate and communication
protocol settings. A maximum of 9600 baud rate is recommended.

The multidrop RS232 cable should be kept to less than three meters in length.

A 12K ohm terminating resistor should be placed on the last connector of the cable (connect
from pin 2 to pin 5 and from pin 3 to pin 5 – refer to Figure 11).

The shielding of the multidrop cable must be continuous throughout the cable.

The shielding of the multidrop cable must only be terminated at one end. It should be connected
to the metal shell of the DB 9 way connector.