Table 4 Modbus Rtu Mode Of Transmission - ABB LVS Digital Manual

With m10x motor controller

Hide thumbs Also See for LVS Digital:

Table of Contents

M OD BUS STA N DARD

Characteristic

Coding System

Number of bits per character:

Start bits

Data bits (least significant first)

Parity

Stop bits

Error Checking

Table 4 Modbus RTU mode of Transmission

2.2.1.5. Error Detection

There are two types of errors, which may occur in a communication system:

• Transmission error and

• Programming or Communication error

The Digital Gateway deals with either type of error as specified in MODBUS specification.

The most frequent cause of communication error is noise, unwanted electrical signals in a

communication channel. These signals occur because of electrical interference from

machinery, damage to the communication channel, impulse noise (spikes), etc. Character

framing, a parity check, and a redundancy check detect these errors. When the error occurs,

the message is unreliable and the processing of the last received erroneous message stops.

Programming or operational errors are those involving illegal data in a message or difficulty in

communicating with a slave. These errors result in an exception response either from Master

or Slave station.

1 2

RTU (8-bit)

8-bit

1 (1 bit set for even or odd parity, no bits for no

parity)

1 or 2

CRC (Cyclical Redundancy Check)

I NTR OD UCT IO N

1 TG C90 80 04

Table of Contents