Command Structure - Planar LookThru LO552 Series User Manual

RS232 Protocol

4. Command Structure

[OPCODE](MODIFIERS)[OPERATOR][OPERANDS][TERM]

OPCODE is the command code (e.g. "GAIN"). This can be written either using the named
command code (see the "Command Code" column in the table) or the numeric command code
(see the "Numeric Command Code" column in the table).

MODIFIERS are modifier values [e.g. "(ZONE.1, ALL)"]. There are zero or more modifiers for
each command. The modifiers can be written either with their named value or their numeric value
(see "Examples" on page 6). See the "Modifiers" column in the table.

OPERATOR is the action to be performed. See the "Operators" column in the table.

'=' writes the setting value.

'?' reads the setting value in name form (see "Examples" on page 6).

'#' reads the setting value in numeric form (see "Examples" on page 6).

'+' increments the setting value.

'-' decrements the setting value.

':' indicates that the message is a response to one of the following operators: =?#+-

'!ERR' indicates that the message is a failure response. An error code will be listed after the
"ERR", with a space before it. Error codes are as follows:

ERR 1: Invalid syntax

ERR 2: [Reserved for future use]

ERR 3: Command not recognized

ERR 4: Invalid modifier

ERR 5: Invalid operands

ERR 6: Invalid operator

'@ACK' indicates that the message is an acknowledgment (ACK) to a command that has no
operator.

'^NAK' indicates that the message is a negative acknowledgment (NAK) to a command. This
indicates that the command was received but cannot be processed at this time.

[No operator] denotes an action. In this case, there's no operator and no operand.

OPERAND indicates the data to be sent with the message. In some cases, there can be multiple
operands. See the "Operands" column in the table.

Enumerated operands can be written either with their named value or their numeric value (see
"Examples" on page 6).

String operands are written with quotation marks at the beginning and end. Example: "this is a
string operand". Special characters, [CR], [LF], " and \ can be included in a string by escaping
them with the \ character (see "Examples" on page 6).

Integer (or signed integer / unsigned integer) are always numeric values.

Fixed point operands are numeric values with fractional parts. They use decimal point
notation.
Planar LookThru Display Series RS232 User Manual
020-1381-00B
RS232 Protocol
Page | 5