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193
Frames
Section 7-2
7.
The result (the value in the CRC register) is placed in the lower byte of the
message.
Example of Appending the Result
If the calculated CRC value is H'1234, this is appended as follows to the
command frame:
7-2-2
Response Frames
Normal Response
Frames
Error Response
Frames
No Response
In the following cases, the received command is not processed and a
response is not returned. A timeout will occur at the host device.
• The slave address in the received command is different from the commu-
nications unit number set in the EJ1.
• A parity error, framing error, or overrun error occurred due to a transfer
error or other error.
• A CRC-16 code error occurred in the received command frame.
• A time interval greater that 3.5 characters occurred between data while
receiving a command frame.
In the following case, the command is processed, but a response is not
returned.
• Broadcast transmission (Slave address: H’00)
Slave
address
Function
code
CRC-16 calculation range
1
1
CRC-16
Low
H'34
High
H'12
Data
2
Bytes:
Slave
address
Function
code
CRC-16 calculation range
1
1
CRC-16
Data
2
Bytes:
Slave address
The unit number that was specified in the command frame is
returned here. This is the unit number of the responding EJ1.
Function code
The function code that was received is returned here.
In an error response frame, "H'80" is added to the value to indicate
that this is an error response.
Example: Received function code = H'03
Function code in error response frame = H'83
Error code
An end code that indicates the error.
CRC-16
Cyclical Redundancy Check
These two bytes are a check code calculated from the slave
address through the end of the data in hexadecimal.
CRC-16 calculation range
Slave
address
Function
code
Error
code
CRC-16
2
1
1
1
Bytes:
Summary of Contents for EJ1 EtherCAT
Page 2: ...EJ1 Modular Temperature Controllers User s Manual Revised July 2008 ...
Page 3: ...iv ...
Page 19: ...xx ...
Page 213: ...188 Detailed Description of Services Section 6 4 ...
Page 227: ...202 Detailed Description of Services Section 7 5 ...
Page 303: ...278 Index ...
Page 305: ......