Echelon Neuron C - Manual (Page 151)

Neuron C Programmer’s Guide 139
Its syntax is the following:
resp_arrives [( msg-tag-name )]
If a response arrives, this event evaluates to TRUE. The event can optionally be
qualified by a message tag name; this qualification limits the event to a response
message that corresponds to a previously sent request that used the named
message tag. When there is no message tag name qualifying the event, the event
evaluates to TRUE for each response message that arrives.
The resp_receive( ) Function
The resp_receive( ) function has the following syntax:
boolean resp_receive(void);
This function receives a response into the resp_in object. The function returns
TRUE if a response is received, otherwise it returns FALSE. The response is
automatically discarded at the end of the task that receives it.
Calling resp_receive( ) has the side-effect of calling post_events( ), so a call to
resp_receive( ) defines a critical section boundary.
Format of a Response
The name of the incoming response object is resp_in.
The incoming response structure is predefined in the Neuron C Compiler as
follows:
struct {
int code; // message code
int len; // length of message data
int data[MAXDATA]; // message data
resp_in_addr addr; // explicit address - see the
// include file
} resp_in;
code A numeric message code in the range 0 to 79. See Message Codes on
page 123.
len The length of the message data.
data The data contained in the message. This field is valid only if len is
greater than 0. MAXDATA is a function of the #pragma
app_buf_in_size (see Chapter 8, Memory Management , on page 173):
MAXDATA = app_buf_in_size – 6
or
MAXDATA = app_buf_in_size – 17
(if explicit addressing is used by any message or network variable in
this program)
addr An optional field in the incoming message that an application
program can use to determine the source and destination of the
message. You can find the definition of the type resp_in_addr in the
include file.