Spectracom Corporation
EPSILON CLOCK MODEL EC1S
EPSILON CLOCK User’s Manual
5-1
5
5
5
5
Remote Control Interface
Remote Control Interface
Remote Control Interface
Remote Control Interface
5.1
5.1
5.1
5.1
General
General
General
General
The remote control interface allows remote configuration and remote status reporting of the
clock. The RS232C connection operates at 9600 bps and is set to 8 bits, 1 stop bit, and odd
parity.
5.2
5.2
5.2
5.2
Protocol
Protocol
Protocol
Protocol
The protocol used is Master (Host) / Slave (EPSILON CLOCK®) with a systematic reply to all
messages. The following exceptions apply (for which no reply is expected):
•
The time code message sent periodically
•
The reset clock command
All messages start with the "STX" character and end with the "ETX" character.
e.g.: <STX> <Message> <ETX>
The characters “ STX ”, “ ETX ” or “ DLE ” to be sent within a message should be escaped
(prefixed) by the "DLE" character.
Each message contains four distinct sections:
•
The message “ID” (this identifies the type of message being sent):
•
The count of the number of data bytes in the message (CNT),
•
The data bytes (DATA
(*)
) of the message,
•
The checksum: calculated by performing an exclusive OR on all the consecutive
characters in the message (ID + CNT + DATA)
e.g.:
<Message> = <ID> <CNT >
<DATA
(*)
>
<CS>
Number of bytes
1
1
N
1
(*): The encoding format of the DATA is based on “MOTOROLA big Endian” type (integer, long,
float, and double data must be sent or received with the MSB first).
NOTE: The maximum length of the <DATA> section is 255 bytes.
Messages belong to one of three categories:
•
Queries (requests for information from the EPSILON CLOCK®)
•
Commands (functions that initialize or configure the EPSILON CLOCK®)
•
Error Messages (returned by the clock if errors are detected in the Queries or
Commands sent by the user)
When a user sends a message to the EPSILON CLOCK®, it replies within the current second.
This reply, or acknowledgement, is formatted as follows:
•
The format of the message is identical to the message sent by the user