Specifications

78 209351 REV B Operations Manual, Redundant System Controllers
In case of Packet Wrapper request frame (Tag 6), data address field used to specify
amount of bytes returned by RCP unit in response frame from local port. Byte
collecting from local port starts immediately after wrapped frame being send out. There
is no time-out and response frame is not being sent back to host PC until specified
amount of bytes collected from Local Port. New request sent by PC host will cancel
byte collecting and all collected bytes will be discarded.
7.2.2.6 Data Length
This byte value specifies amount of bytes attached in Data Filed. For Get command it
specifies the number of data bytes that has to be returned by RCP unit to a host PC in
Response frame. For Set command value of this byte specifies number of data fields to
be accessed starting from the address specified in the Data Address byte. In general,
Data Length value plus Data Address must not exceed the maximum data size
particular tag.
7.2.2.7 Data Field
The actual data contained in the packet must be placed in this field. The “Get Request”
type of command must not contain any Data Field. “Get Request” will be rejected if any
data is present in the Data Field. Generally, the Bad Checksum error code will be add-
ed to the response from the unit. In case the data length is 2 bytes, each data word is
placed in the frame with its least significant byte first. All data with length of 2 bytes
must be represented as integer type with maximum value range from 32767 to
(-32767). Formatting of data bytes for the Packet Wrapper frame is not important for
the RCP unit. All data bytes will be redirected to the RCP2 local port without any modi-
fication.
Error Code name
Byte
Value
Possible Cause
No Errors 0 Normal Condition, no errors detected
Data Frame Too Big 1 Specified Data length is to big for respondent buffer to accept
No Such Data 2 Specified Data Address is out off bounds for this tag data
Bad Value 3 Specified value not suitable for this particular data type
Read Only 4 Originator tried to set a value which has read only status
Bad Checksum 5 Trailer checksum not matched to calculated checksum
Unrecognizable error 6
Error presented in originator frame, but respondent failed to
recognize it. All data aborted.
Table 7-3: Error Status Byte Values