4.1 General command syntax

The IO-FEP knows a number of parameters, each identified by a parameter name. To set a certain parameter to a new value, a message:

name=value

has to be sent to the IO-FEP. The IO-FEP interprets this command, checks the range of value , sets the internal parameter and then answers:

name=value

The value in the reply is the value actually recognized by the IO-FEP. For instance, if the requested value was out of range, the replied (and internally used) value is limited to the applicable minimum or maximum.

To read a parameter from the IO-FEP, instead of a new parameter value a question mark is sent:

name=?

The IO-FEP replies the actual value in a complete message:

name=value

A complete list of the parameter the IO-FEP knows is shown later in this document in chapter Parameter list . Below, some common rules applying to the remote control message syntax are summarized.

• Parameter names always are of lower case letters, most of them are four characters long.
• Non-numeric parameter values always are written in upper case.
• Numeric (floating point) values may be specified with an arbitrary precision, however the device will reply only a fixed number of places. The IO-FEP recognizes a decimal point ('.'), numbers must not contain any commas.
• There must not be any whitespace in front or after the '=' in a message.
• If the command/query is not of the form name=value or name=? , the IO-FEP replies the message ?SYNTAX .
• If the message syntax is OK, but contains an unknown parameter name is used, the reply is ?UNKNOWN
• Numeric parameters are cut to the limits defined for this particular parameter.
• Misspelled choice values cause the IO-FEP to set the first value of the choice list.
• Assigning a value to a read-only parameter will cause no fault, however the IO-FEP will overwrite this parameter immediately or some seconds later with the actual value.