Table of Contents
Advertisement
The user's computer generates and sends packets to the CHPA that can contain only one
command and associated parameters. The CHPA can process only one received packet at a
time; packets are not queued for processing. If a command is sent to the CHPA CIF port, a
response will be returned usually within 100 ms. Commands requiring long execution times,
such as changing power level, generate an immediate response indicating if the command was
accepted and whether or not execution has begun.
If the CHPA was able to execute a command received via the CIF, the response message will
indicate what command was executed and return any necessary parameters. In the case of a
query command, the returned parameters are referred to as status bytes and are described in
detail later in this section.
If the CHPA was not able to execute a command received via the CIF, a reject code (or codes) is
included in the response message. If the STX/ETX header/ending byte message format was
used, the header byte is NAK, thus indicating a rejection.
3.9 Command and Response Format
Command Received by CHPA:
HEADER
ADDRESS
BYTE
BYTE
Response Returned When Command is Accepted:
HEADER
ADDRESS
BYTE
BYTE
Response Returned When Command is Rejected:
HEADER
ADDRESS
BYTE
BYTE
To avoid problems with control characters, and so on, device addresses, commands,
parameters, and responses are limited to standard ASCII values 32 through 126.
3.9.1
Header and Ending Bytes
(Header and ending bytes are under CIF CONFIGURATION as PROTOCOL.)
Two message formats are supported: STX/ETX header/ending bytes and printable ASCII
header/ending bytes.
STX/ETX option (STX/ETX on front panel)
Commands:
Header byte = STX (ASCII 02)
Ending byte = ETX (ASCII 03)
D
.01023245 R
.R
OC
EV
COMMAND
BYTE
COMMAND
BYTE
COMMAND
BYTE
THIS DOCUMENT IS THE PROPERTY OF COMMUNICATIONS & POWER INDUSTRIES.
REPRODUCTION OR RELEASE WITHOUT EXPRESS PERMISSION IS STRICTLY PROHIBITED
PARAMETERS
ENDING
AS REQUIRED
BYTE
PARAMETERS
ENDING
BYTE(S)
BYTE
PARAMETERS
ENDING
CODE(S)
BYTE
CHPA S
ERIES
CHECK
BYTE
CHECK
BYTE
CHECK
BYTE
3-9
Advertisement
Table of Contents
