Santerno Sinus Penta - Serial Communications; MODBUS-RTU PROTOCOL

SINUS PENTA
PROGRAMMING GUIDE
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50. SERIAL COMMUNICATIONS
50.1. Overview
Sinus Penta drives may be connected to other devices through a serial link. This allows reading and writing the
parameters accessed through the remotable display/keypad..
Elettronica Santerno also supplies the RemoteDrive software
package allowing controlling the drive through a computer
connected via serial link.
The RemoteDrive offers the following functionality: image copy,
keypad emulation, oscilloscope functions and multifunction tester,
data logger, history data table compiler, parameter setting and
data reception–transmission–storage from and to a computer, scan
function for the automatic detection of the connected inverters (up
to 247 connected inverters).
Elettronica Santerno also supplies the RemoteDrive software package for the inverter control through a computer
connected via serial link.
50.2. MODBUS–RTU PROTOCOL
Messages and data are sent by means of standard protocol MODBUS in RTU mode. This standard protocol performs
control procedures using an 8–bit binary representation.
In RTU mode, a message begins with a silence interval equal to 3.5 times the transmission time of a character.
If the character transmission stops for a time equal to 3.5 times the transmission time of a character, the controller will
consider this time interval as the end of the message. Similarly, a message starting with a shorter silence time is
considered as part of the previous message.
Message
beginning
Address
Function
Data
Error control
End of message
T1–T2–T3–T4
8 bits
8 bits
n x 8 bits
16 bits
T1–T2–T3–T4
Use parameter R004 (TimeOut) to increase the silence time interval up to max. 10000ms for the systems that do not
recognize standard timeouts.
Address
The address field acknowledges any value ranging from 1 to 247 as the address of the slave peripheral device. The
master device queries the peripheral device specified in the address field; the peripheral device will respond with a
message containing its address to let the master device know which the slave source of the response is. A master
device query with a 0 address is addressed to all slave devices, which will not respond at all (broadcast mode).
Function
The function related to the message may be chosen within the legal field ranging from 0 to 255. A response of the slave
device to a message of the master device will simply return the function code to the master device if no error took place;
otherwise, the most significant bit in this field is set to 1.
The only functions allowed are 03h: Read Holding Register, 06h Write Single Register and 10h: Preset Multiple
Register (see below).