Amada Miyachi Unitek STA-100A, Operation Manual, Page: 120 / 154

APPENDIX J: COMMUNICATION OPTION
STA SERIES AC CONTROLS
J-4 990-351
Section II. Communications Protocol and Commands
Communication External Protocol
Each external command will be formatted as follows:
<soh> <@> <cmd> <cnt> <data> <cksum> <eot>.
Definition of Command Elements
<soh> 1 BYTE The data packet will start with a SOH (start of header 0x01 ) character .
<@> 2 BYTES This is the address of the unit to which data is requested converted into
ASCII decimal numbers.
(“01" - “30").
<cmd> 2 BYTES This is a two character ASCII string denoting the command.
(i.e. “IA”) .
<cnt> 2 BYTES This is a count of data bytes to follow, converted into a ASCII HEX
number.
(“00" - “FF").
<data> n BYTES his is optional BINARY data.
Multiple binary byte ordering [MSB][…][LSB] .
<cksum> 2 BYTES This is a two charter ASCII HEX string calculated from the sum of all
fields except
<soh>, <cksum>, and <eot> . Then masked with 0xFF.
<eot> 1 BYTE This terminates the transmission. (End transmit 0x04 ).
Unit Responses To External Commands
Errors or Unsupported Commands
The STA will respond with a Negative Acknowledge < NAK > (0x15) when an error in checksum is
encountered. The host will return a Negative Acknowledge < NAK > in response to any command that is
not supported.
<soh> <@> < NAK > <err> <cksum> <eot>
Where <err> = ‘1’ NO <SOH> ‘5’ HC16 is Busy
‘2’ BAD checksum ‘6’ Data Bad
‘3’ Unrecognized command ‘7’ Input timeout
‘4’ Timeout ‘8’ Output timeout
Valid Commands
A valid command will return either data or
<ACK> (0x06) .
<soh> <@> <ACK> <cksum> <eot>
Data will be returned with the following structure:
<soh> <@> <cmd> <cnt> <data> <cksum> <eot>