Siemens SIMATIC TI500 Manual do Utilizador descarregar pdf (Página 51)

Modbus Commands

C-2

TIWAY I Gateway User Manual

C.1 Modbus Protocol Overview

This

appendix describes the Modbus protocol in detail. For each of the

Modbus functions described, examples of requests and responses are given.

able C-1 describes the Modbus functions supported by the Gateway

able C-1

Modbus Functions Supported

Code Type Description

01 Read Coil Status Get current status of a group of coils.

02 Read Input Status Get current status of a group of discrete

inputs.

03 Read Holding Register Get current values from holding registers.

04 Read Input Register Get current values from input registers.

05 Force a Single Coil Change the state of a logic coil to On or

Off, forced On or forced Off, or unforced.

06 Write a Single Register Write a value into a holding register.

07 Read Exception Status Get the 8 internal status coil values.

08 Execute Diagnostics Send diagnostic tests to a slave.

11 Get Communications

Event Counter

Enable the success or failure of a query to

be determined.

12 Get Communications

Event Log

Get the communications log for Modbus

network transactions.

15 Write Multiple Coils Change a number of consecutive coils.

16 Write Multiple Registers Write values into a series of consecutive

holding registers.

The

TIW

Y I Gateway operates in the RTU transmission mode. The RTU

mode determines the start and finish of a message based on a time period of

silence (no transmission) equivalent to the time it would take to transmit

3.5 characters at the chosen baud rate. The RTU transmission frame is

shown in Figure C-1.

bits

8 bits

n x 8 bits

16 bits

Address Function Data Checksum

T1 T2 T3

T1 T2 T3 . . . represents a time of 3.5 characters at given baud rate.

I000000

No data

Figur

e C-1

RTU

ransmission Frame

The R

ransmission Frame

1 2 ... 46 47 48 49 50 51 52 53 54 55 56 ... 93 94

Comentários a estes Manuais

Sem comentários

Siemens SIMATIC TI500 Manual do Utilizador Página 51

Comentários a estes Manuais

Manuais e produtos relacionados com Gateways/controladores Siemens SIMATIC TI500