Can we use unconnected messaging with multi service request?

[salma4791]

Hi,

Can we use use_connected_msg=0 and allow_packing=1? MSR is not working for me using unconnected messaging. It is sending one request at a time even though the allow_packing option is set to 1.

Am using Allen-Bradley 1756-L73 ControlLogix PLC.

[salma4791]

I further analyzed the code and figured out that get_payload_size(request) is only for connected messaging and for UCMM it is giving INT_MAX due to which the Bundle is not being formed and it is crashing.

/* how much space do we have to work with. */
remaining_space = session->max_payload_size - (int)sizeof(cip_multi_req_header);

        if(vector_length(session->requests)) {
            do {
                request = vector_get(session->requests, 0);

                remaining_space = remaining_space - get_payload_size(request);

                /*
                 * If we have a non-packable request, only queue it if it is the first one.
                 * If the request is packable, keep queuing as long as there is space.
                 */

                if(num_bundled_requests == 0 || (request->allow_packing && remaining_space > 0)) {
                    //pdebug(DEBUG_DETAIL, "packed %d requests with remaining space %d", num_bundled_requests+1, remaining_space);
                    bundled_requests[num_bundled_requests] = request;
                    num_bundled_requests++;

                    /* remove it from the queue. */
                    vector_remove(session->requests, 0);
                }
            } while(vector_length(session->requests) && remaining_space > 0 && num_bundled_requests < MAX_REQUESTS && request->allow_packing);

Here the get_payload_size(request) function gets the size only for connected service.
int get_payload_size(ab_request_p request)
{
int request_data_size = 0;
eip_encap *header = (eip_encap *)(request->data);
eip_cip_co_req *co_req = NULL;

pdebug(DEBUG_DETAIL, "Starting.");

if(le2h16(header->encap_command) == AB_EIP_CONNECTED_SEND) {
    co_req = (eip_cip_co_req *)(request->data);
    /* get length of new request */
    request_data_size = le2h16(co_req->cpf_cdi_item_length)
                        - 2  /* for connection sequence ID */
                        + 2  /* for multipacket offset */
                        ;
} else {
    pdebug(DEBUG_DETAIL, "Not a supported type EIP packet type %d to get the payload size.", le2h16(header->encap_command));
    request_data_size = INT_MAX;
}

pdebug(DEBUG_DETAIL, "Done.");

return request_data_size;

}

Since the payload size is INT_MAX incase of unconnected send, it is giving negative value and crashing.

[kyle-github]

Huh... I wonder why I did that? That doesn't look right, but maybe there is some protocol difference on some PLCs? I will see if I can get to this in the next week. This does look like a bug.