General Monitors FL3112, Руководство пользователя

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Model FL3112
25
7.4.3 Function Codes Supported
Function Code 03 (Read Holding Registers) will be used to read status from the slave unit.
Function Code 06 (Preset Single Register) will be used to write a command to the slave
unit.
7.5 Exception Responses and Exception Codes
In a normal exchange, the master device sends a query to the FL3112. The FL3112
receives the query and returns a normal response to the master. If a communications error
occurs, the FL3112 will return an exception response.
7.5.1 Exception Responses
Byte Modbus Range Referenced to FL3112
1
st
Slave Address 1-247* (Decimal) FL3112 ID (Address)
2
nd
Function Code 83 or 86 (Hex) MSB is set with Function Code
3
rd
Exception Code 01 – 06 (Hex) Appropriate Exception Code
(See below)
4
th
CRC Lo 00-FF (Hex) CRC Lo Byte
5
th
CRC Hi 00-FF (Hex) CRC Hi Byte
Function Code Field: In a normal response, the FL3112 echoes the function code of the
original query in the function code field of the response. All the Function Codes have a
most-significant bit (MSB) of zero (0).
In an exception response, the FL3112 sets the MSB of the function code to a one (1). With
the function code’s MSB set, the master can recognize the exception response and can
process the data field for the exception code from the FL3112 response message.
Exception Code Field: In a normal response, the FL3112 returns data and status in the
data field, which was requested in the query from the master. In an exception response,
the FL3112 returns an exception code in the data field, which describes the FL3112
condition that caused the exception. Below is a list of exception codes that are supported
by the FL3112: