Using Port 1 "Modbus Rtu; Autobaud Port 1" Procedure - gefran GPC 40-600A Use And Installation Manual

Advanced power controllers

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A network typically has a Master that "manages" communication by means of "commands," and Slaves that carry out

these

commands.

GPC should be considered as a Slave to the network Master, which is normal a supervisory terminal or a PLC. It is uniquely

identified by a node address (ID) set on the rotary switches (tens + units). Up to 99 GPC modules can be installed in a serial

network, with node address selectable from '01' to '99'. The use of the letters (A...F) on the rotary switches is reserved.

GPC has a Modbus RTU serial port (PORT 1) an optional serial port (see ordering code) for the Fieldbus (PORT 2). The

Fieldbus can use one of the following protocols: Modbus RTU, Profibus DP, CANopen, Profinet, Ethernet/IP and Ethernet

Modbus TCP.

PORT 1, the Modbus RTU port, has the following factory settings (default):

The use of the letters (A...F) on the rotary switches is re-

served.

5.3.1.

"AutoBaud Port 1" procedure

The AutoBaud procedure allows the correct BaudRate

value to be set automatically by detecting the Master's

transmission frequency.

This procedure is essential for the correct use of the PORT

1 Modbus RTU port. The serial communication speed and

parity of the GPC modules must always be adjusted to the

connected supervision terminal or PLC.

AutoBaud is executed on the GPC as follows:

Connect the serial cables to all modules in the network

on PORT 1 and to the supervision terminal.

Set the rotary switch on the GPC modules to be

installed, or on all modules present in case of first

installation, to position "0+0".

Check that the green "STATUS" LED flashes at a high

frequency (10 Hz).

The supervision terminal must send a series of generic

"MODBUS" read messages to the network.

The procedure is complete when all the green L1

"STATUS" LEDs on the GPC modules flash at a normal

frequency (2 Hz). NOTE: The frequency is valid if pa-

rameter 197 Ld.1 is equal to 16 by default.

The new speed parameter is permanently saved

in each GPC; therefore the "AUTOBAUD SERIAL"

sequence does not have to be run in subsequent

power-ups.

NOTES:

•

When the rotary switch is turned, the green "STATUS"

LED stays on for about 6 seconds, after which it re-

sumes normal operation and saves the address.

•

The green LED L1 "STATUS", mentioned in the proce-

dure, can vary its behaviour according to the parame-

terLd.1, which by default is equal to 16.