USA57 Revision
1.2
85
Example Initialization Error Response:
Note that the Upper Nibble only typically takes on values of 4 or 6 (Hex)
An initialization error has response has 1 in the lower Nibble. So the response is 41 Hex or 61
Hex, which corresponds to ASCII character upper case “A” or lower case “a”, depending on if
the device is busy or not.
Example Invalid Command Response:
Note that the Upper Nibble only typically takes on values of 4 or 6 (Hex)
An invalid command has response has 2 in the lower Nibble. So the response is 42 Hex or 62
Hex, which corresponds to ASCII character upper case “B” or lower case “b”, depending on if
the device is busy or not.
Example Operand Out of range Response:
Note that the Upper Nibble only typically takes on values of 4 or 6 (Hex)
An operand out of range has response has 3 in the lower Nibble. So the response is 43 Hex or
63 Hex, which corresponds to ASCII character upper case “C” or lower case “c”, depending on
if the device is busy or not.
Example Overload Error Response:
Note that the Upper Nibble only typically takes on values of 4 or 6 (Hex)
An overload error has response has 7 in the lower Nibble. So the response is 47 Hex or 67 Hex,
which corresponds to ASCII character upper case “I” or lower case “i”, depending on if the
device is busy or not.
Example Response to command /1?4
FFh: RS485 line turn around character. It’s transmitted at the beginning of a message.
2Fh: ASCII “/”Start character. The DT protocol uses the ‘/’ for this.
30h: ASCII “0” This is the address of the recipient for the message.
In this case ASCII zero (30h) represents the master controller.
57h: This is the status character (as explained above
31h:
31h: These two bytes are the actual answer in ASCII.
This is an eleven which represents the status of the four inputs.
The inputs form a four bit value. The weighting of the bits is:
Bit 0 = Switch 1
Bit 1 = Switch 2
Bit 2 = Opto 1
Bit 3 = Opto 2
03h: This is the ETX or end of text character. It is at the end of the answer string.
0Dh: This is the carriage return…
0Ah: ...and line feed.