Emerson Rosemount 370XA, System Reference Manual

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370XA Gas Chromatograph System Reference Manual
APRIL 2014 7P00370-H01
3 - 53
3.14.9 Configure the serial communications settings from
the 370XA
To configure the serial port communication settings to communicate
with ModBus host devices such as a flow computer, RTU, SCADA, or
DCS, the protocol settings for all the devices on the network must
match. Obtain the required serial port settings prior to configuring the
settings on the GC.
1. Go to the Main Menu and select Communications on the
Application menu. The Communications screen opens.
2. Enter the serial port settings.
(a.)
Modbus ID - The address that the host device will use
to communicate with the GC. For applications where the
GC is the only slave device on the network, the ModBus
ID is typically set to 1. For multi-dropped applications
where the GC is one of several on the serial network,
the ModBus ID needs to be unique. Refer to your host
device configuration to determine the ModBus ID to be
configured on the GC.
(b.) Baud Rate - The baud rate can be set at the standard
rates from 1200 baud up to 57600. For ModBus commu-
nications, the typical setting is
9600 .
(c.) Data Bits - The number of bits used for communica-
tions. The typical setting for ASCII mode
communications is
7 . The typical setting for RTU mode
communications is 8 .
(d.) Stop Bits - The number of bits sent to indicate the end
of a message. Typically set to 1 .
(e.) Parity - The error checking mode for the parity bit in
ASCII mode messages. This can be set to either ODD
or EVEN for ASCII mode communications and must
match the host device’s setting. Set to NONE for RTU
mode communications.
(f.) MAP File - The ModBus address map. By default, this is
set to SIM_2251, which is a pre-configured map with the
same mapping as the Daniel 2251 controller, and is the
most common communication mapping for flow