Despatch Protocol Plus Modbus Communications Manuale Utente Scaricare il pdf (Pagina 27)

Chromalox Instruments and Controls

A-51643 Rev. 6 10/06/03 21

Return Slave No Response Count

Number of messages addressed to the

slave for which no response was

returned.

Return Bus Character Overrun Count

Number of overrun and framing errors.

Table 10 Protocol

Plus Exception Code Set

Exception Code

Description

Comments

Illegal Function

The function code received is not valid or

is not supported.

Illegal Data Address

The data address received is invalid or is

not accessible due to security setting.

Illegal Data Value

The data value received is invalid.

5.2 Register and I/O Function Set Description for Protocol

Plus

5.2.1 [01] Read Outputs

Class 1 command. Reads the On/Off status of discrete outputs in the slave. Broadcast is not supported.

Query

The query message specifies the starting output and quantity of outputs to be read. Outputs are addressed

starting at 0.

Example: Query to read outputs 20 . . . 56 from slave address 17.

Field Name

Data

Slave address

$11

Function

$01

Starting address hi

$00

Starting address lo

$13

Number of outputs hi

$00

Number of outputs lo

$25

CRC

$----

1 2 ... 22 23 24 25 26 27 28 29 30 31 32 ... 52 53

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