Configuring Communications; Toggling Communication Modes; Toggling Via Hmi - ABB LWT300 Series User Manual

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C h a p t E R 8

Configuring communications

There are two types of communication at play in the Modbus LWT300 instruments. For general data
exchange operations with external computer systems (PCs, flow computers, etc.) communications go
over the Modbus protocol (Modbus RTU with 2-wire half-duplex RS-485 serial interface). For instrument
configuration (with software tools running on a computer), the HART communication protocol is used
(via a RS-485 serial interface).
NOTICE
The Modbus protocol was never designed for configuration tasks. Thus, it cannot be used
to configure a LWT300 remotely.
Communication parameters for these protocols are set from the Communication menu.
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Figure 48 The Communication menu

Toggling communication modes

LWT300 instruments always operate in one of two modes: Operation or Configuration. Operation mode
is the normal mode for data exchange over the Modbus protocol and Configuration mode is the mode
to use when configuring the instrument over the HART protocol. These modes can be set either in
software of hardware.

Toggling via HMI

To toggle communication mode via the instrument HMI:
1 From the Communication menu, select Device Mode.
2 Click Edit and select Operation (Modbus) or Configuration (HART), as necessary.
3 Click OK. Your instrument is now in communicating in the mode that you chose.
NOTICE
If communication does not seem to work after toggling communication mode, verify the
communication parameters set via the dip switches (next page).