Sinee EM500 - Function Code 0 X03 Read Multiple Registers or Status Bytes; EM500 Defined Function Code

EM500 Open-Loop Vector Control Inverter User Manual
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As shown in Table 12-1, EM500 inverters mainly involve common function codes,
for example 0x03 read multiple registers or status words, 0x06 write single register or
command, 0x10 write multiple registers or commands, and 0x08 diagnosis function code.
Besides, to perform some special functions, for example write register RAM and not
to save in EEPROM, user should define 0x41 as write single register or command (no to
save) and 0x42 as write multiple registers or commands in the user-defined function code
area (no to save).
After receiving abnormal valid data from device, relevant abnormal information (see
12.3.7 Abnormal Information Response) will be returned. For distinguishing it from the
normal communication data, abnormal function codes are defined. Similar to normal
request function code, abnormal function code = request function code + 0x80.
Table 12-1 EM500 Defined Function Code
Function
Code
Abnormal
Function Code
Function
03
83
Read multiple registers or status bytes
41
C1
Write single register or command (not to save)
42
C2
Write multiple registers or commands (not to save)
08
88
Diagnosis function code
06
86
Write single register or command
10
90
Write multiple registers or commands
In the following sections, those PDU parts that are different due to functions shall be
explained in detail.
12.3.3.1 Function Code 0x03 Read Multiple Registers or Status Bytes
In a remote device, inverter uses this function code to read the content of the
continuous blocks of the holding register. The request PDU indicates the start register
address and the Number of Registers.
Divide register data of the response message into two bytes for each register. For
each register, the first byte includes high bit, the second byte includes low bit.

Request PDU