Parsing Active COV Subscription Request Responses

[Randy Yates]

I have searched and cannot find a function in the sourceforge project for this. Have I missed it? If not, does anyone know of a place on the web it is available? I've googled and couldn't find anything except the wireshark parser.

Thanks in advance.

[Randy Yates]

To be more precise, I should have stated "Parsing ReadProperty request responses for the BACNET_PROPERTY_ACTIVE_COV_SUBSCRIPTIONS property."

[Steve Karg]

Here is one way to parse the property:

/* BACnetCOVSubscription */
int decode_cov_subscription(
    uint8_t * apdu,
    int max_apdu_len,
    BACNET_COV_SUBSCRIPTION * covs)
{
    int apdu_len = 0;
    int len = 0;
    int tag_len;
    uint32_t len_value_type = 0;
    uint8_t tag_number = 0;

    /* recipient [0] BACnetRecipientProcess,  */
    len =
        decode_context_recipient_process(&apdu[apdu_len], 0, &covs->recipient);
    if (len < 0)
        return BACNET_STATUS_ERROR;
    apdu_len += len;
    /* monitoredPropertyReference [1] BACnetObjectPropertyReference,  */
    len =
        bacapp_decode_context_obj_property_ref(&apdu[apdu_len], 1,
        &covs->monitoredPropertyReference);
    if (len < 0)
        return BACNET_STATUS_ERROR;
    apdu_len += len;
    /* issueConfirmedNotifications [2] BOOLEAN,  */
    tag_len =
        decode_context_boolean2(&apdu[apdu_len], 2,
        &covs->issueConfirmedNotifications);
    if (tag_len < 0)
        return BACNET_STATUS_ERROR;
    apdu_len += tag_len;
    /* timeRemaining [3] Unsigned,  */
    tag_len =
        decode_tag_number_and_value(&apdu[apdu_len], &tag_number,
        &len_value_type);
    apdu_len += tag_len;
    if (tag_number != 3)
        return BACNET_STATUS_ERROR;
    apdu_len +=
        decode_unsigned(&apdu[apdu_len], len_value_type, &covs->timeRemaining);
    /* covIncrement [4] REAL OPTIONAL */
    if (decode_is_context_tag(&apdu[apdu_len], 4) &&
        !decode_is_closing_tag(&apdu[apdu_len])) {
        tag_len = decode_context_real(&apdu[apdu_len], 4, &covs->covIncrement);
        if (tag_len < 0)
            return BACNET_STATUS_ERROR;
        apdu_len += tag_len;
    } else
        covs->covIncrement = 0.0f;
    return apdu_len;
}

[Randy Yates]

Thanks so much, Steve! Also the answer to the tag. I see a lot of the information I was missing in section 20.2 of the spec, but I guess I was too thick to see it right off!