Emerson 2202, Руководство для продвинутых пользователей

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Introduction
Parameter
x.00
Parameter
description format
Keypad and
display
Serial
communications
CT Modbus
RTU
PLC Ladder
programming
CTSoft Menu 0
Advanced parameter
descriptions
22
Commander SK Advanced User Guide
www.controltechniques.com Issue Number: 9
Writes when actual parameter type is different from selected
The slave will allow writing a 32 bit value to a 16 bit parameter as long as the 32 bit value is within the normal range of the 16 bit parameter.
The slave will allow a 16 bit write to a 32 bit parameter. The slave will sign extent the written value, therefore, the effective range of this type of write
will be ±32767.
Examples, if Pr
20.21 has a range of ±100000, and Pr 20.22 has a range of ±10000.
6.1.9 Exceptions
The slave will respond with an exception response if an error is detected in the master request. If a message is corrupted and the frame is not
received or the CRC fails then the slave will not issue an exception. In this case the master device will time out. If a write multiple (FC16 or FC23)
request exceeds the slave maximum buffer size then the slave will discard the message. No exception will be transmitted in this case and the master
will time out.
Exception message format
The slave exception message has the following format.
Read
Start
register
address
Number
of 16bit
registers
Response Comments
Pr 20.21 2020 1 0x5678
Standard 16 bit access
to a 32bit register will
return low 16bit word of
truncated data
Pr 20.21 18404 2 0x12345678 Full 32bit access
Pr 20.21 18404 1 Exception 2
Number of words must
be even for 32bit access
Pr 20.22 2021 1 0xABCD
Standard 16 bit access
to a 32bit register will
return low 16bit word of
data
Pr 20.22 18405 2 0xFFFFABCD
32bit access to a 16bit
register will return 32bit
sign extended data
Pr 20.23 18406 2 0x00000123
32bit access to a 16bit
register will return 32bit
sign extended data
Pr 20.21 to
Pr 20.22
2020 2
0x5678,
0xABCD
Standard 16 bit access
to a 32bit register will
return low 16bit word of
truncated data
Pr 20.21 to
Pr 20.22
18404 4
0x12345678,
0xFFFFABCD
Full 32bit access
Write
Start
register
address
Number
of 16bit
registers
Data Comments
Pr 20.21 2020 1 0x1234
Standard 16 bit write to a
32bit register. Value
written = 0x00001234
Pr 20.21 2020 1 0xABCD
Standard 16 bit write to a
32bit register. Value
written = 0xFFFFABCD
Pr 20.21 18404 2 0x00001234
Value written =
0x00001234
Pr 20.22 2021 1 0x0123 Value written = 0x0123
Pr 20.22 18405 2 0x00000123
Value written =
0x00000123
Byte Description
0 Slave source node address
1 Original function code with bit7 set
2 Exception code
3 CRC LSB
4 CRC MSB