8 RS232 Event Generation/Text Insertion Protocol

8.1 Message Structure

The Delimiter byte signals the start of a new message, and has a value of 0xFF.

The Class and Command fields identify the type of message.

The Data Length is a 16-bit value indicating the number of bytes in the Data portion of the message. Data Length is sent using Intel byte ordering (Little Endian).

The Check Sum byte is the result of XORing all the bytes in the message.

Delimiter

Class

Command

Data Length

Data

Check Sum

8.2 Message Type

One message is currently supported to store text along with recorded video.

CMD_NEW_ADD_TEXT

Class byte is 0x14.

Command byte is 0x40.

Data Length is the number of data bytes in the message (from 2 to 502).

Camera byte indicates the camera associated with the text. The valid range is from 0 to 15.

Alarm/Event byte usage is described in the following section.

String field contains text characters. The string can be from 0 to 500 characters in length.

8.3 Alarm/Event Field

0xFF

0x14

0x40

Data Length[0]

Data Length[1]

Camera

Event

String[0]

String[1]

:

String[n-1]

Check Sum

The two least significant bits are currently used for the event. Bits 2 and 3 are used for Alarm

MSB 7

 

 

 

 

 

 

LSB 0

 

 

 

 

 

 

 

 

0

0

0

0

A

A

E

E

 

 

 

 

 

 

 

 

A – Alarm/Event 0x00

If both the start and end bits are clear, the associated text will be stored with the next recorded field for that camera. That cameras record rate will not be changed.

B – Alarm/Event 0x01

If only the start bit is set, the associated text will be stored with the next recorded field for that camera. This will cause the selected camera, as well as any pre-event fields to be recorded at the Alarm or Event Record Rate.

C – Alarm/Event 0x02

If only the end bit is set, the associated text will be stored with the next recorded field for that camera. This will start the post-event timer** after which, the selected camera will resume recording at the normal record rate*.

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Kalatel DVMRe Triplex

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GE DVMRe user manual Message Structure, Message Type, Alarm/Event Field