Example, ¥ Command receive verification

RS-232C Interface

3.Protocol

■Receiving format (personal computer → VTR)

General format: stx command [:data] [;command [:data]] etx

stx:

02h (HEX)

;(semicolon): 3Bh command delimiter command: ccc

ccc:command (3 ASCII characters)

: (colon):	3Ah parameter delimiter
data:	parameter (any number: based on command)
etx:	03H
	In some cases, the format does not contain what is enclosed in the square brackets.

■Example

stxO S Petx (stop command)

02,4F,53,50,03 (stop command in HEX notation)

■Sending format (personal computer ← VTR)

¥Command receive verification

ack (with error-free receipt of command)

nak e (when communication error has occurred)

e:error code 1: parity error

3: framing error

4: overrun error

¥Response message

General format: stx message [:data] etx

¥Error message (when error has occurred in protocol or command) General format: stx error message etx

ack:06h

nak:15h

stx:02h

message: mmmm

mmmm:message (any number of ASCII characters)

: (colon):	3Ah parameter delimiter
data:	parameter (any number)

error message: ERnnn (error code) nnn: 3-digit number

001:Invalid command (not supported)

002:Invalid parameter

003:Receive buffer overflow

004:Defective connection

etx:03h

■Explanatory description

¥As soon as the receive buffer becomes full, receive buffer overflow is returned, and subsequent commands are canceled.

¥The ACK or NAK response must commence within 20ms.

¥When a new command has been received during the processing of an non-interruptible command, the receive verification code is returned within 20ms, after which the applicable ERROR code is returned, and the processing of the previous command is resumed.

¥When it takes time for execution to be completed, it is to be possible for the next command to be processed (in principle, after the ACK response) without waiting for the completion of the said execution. (This applies only to commands whose processing can be interrupted.)

¥When a command which does not entail a transfer of the deck mode is received, the message of having completed the received command is returned regardless of the deck mode.