[etherlab-users] EtherCAT datagram size

[peak peak]

Hi everyone,

There's a concern with the PDO size that I am not clear and I'd like to ask:

- The size of the EtherCAT frame is not fixed, i.e. when running and capturing 
with wireshark, after every "reasonable" frame (the frames which I configured 
the bytes in), there's a frame with a added 14-byte datagram whose command is 
'FPRD' (Configured Address Physical Read ). This makes me confused. Can anyone 
explain for me?

- The EL2262 takes 7bytes in the PDO. I don't understand why this takes so much 
space? It has only two outputs, and I used only:
const static ec_pdo_entry_reg_t domain_regs[] = {     
   { EL2262SlavePos, Beckhoff_EL2262, 0x7000, 0x01, &off_dig_out1},         
     {}
};

Thank you in advance!
============================================
//EL2262

ec_pdo_entry_info_t slave_6_pdo_entries[] = {
    {0x7800, 0x01, 16}, /* Cycle Counter0 */
    {0x7000, 0x01, 1}, /* Output0 */
    {0x7200, 0x01, 8}, /* Output0 */
    {0x0000, 0x00, 1},
    {0x0000, 0x00, 2},
    {0x0000, 0x00, 3},
    {0x0000, 0x00, 4},
    {0x0000, 0x00, 5},
    {0x0000, 0x00, 6},
    {0x0000, 0x00, 7},
    {0x7800, 0x02, 16}, /* Cycle Counter1 */
    {0x7000, 0x02, 1}, /* Output1 */
    {0x7200, 0x02, 8}, /* Output1 */
    {0x0000, 0x00, 1},
    {0x0000, 0x00, 2},
    {0x0000, 0x00, 3},
    {0x0000, 0x00, 4},
    {0x0000, 0x00, 5},
    {0x0000, 0x00, 6},
    {0x0000, 0x00, 7},
    {0x1d09, 0x98, 32}, /* StartTimeNextOutput */
};

ec_pdo_info_t slave_6_pdos[] = {
    {0x1700, 1, slave_6_pdo_entries + 0}, /* CycCount0 */
    {0x1600, 1, slave_6_pdo_entries + 1}, /* Sample0 */
    {0x1800, 1, slave_6_pdo_entries + 2}, /* Sample0 */
    {0x1710, 1, slave_6_pdo_entries + 3}, /* Gap */
    {0x1711, 1, slave_6_pdo_entries + 4}, /* Gap */
    {0x1712, 1, slave_6_pdo_entries + 5}, /* Gap */
    {0x1713, 1, slave_6_pdo_entries + 6}, /* Gap */
    {0x1714, 1, slave_6_pdo_entries + 7}, /* Gap */
    {0x1715, 1, slave_6_pdo_entries + 8}, /* Gap */
    {0x1716, 1, slave_6_pdo_entries + 9}, /* Gap */
    {0x1701, 1, slave_6_pdo_entries + 10}, /* CycCount1 */
    {0x1680, 1, slave_6_pdo_entries + 11}, /* Sample1 */
    {0x1880, 1, slave_6_pdo_entries + 12}, /* Sample1 */
    {0x1718, 1, slave_6_pdo_entries + 13}, /* Gap */
    {0x1719, 1, slave_6_pdo_entries + 14}, /* Gap */
    {0x171a, 1, slave_6_pdo_entries + 15}, /* Gap */
    {0x171b, 1, slave_6_pdo_entries + 16}, /* Gap */
    {0x171c, 1, slave_6_pdo_entries + 17}, /* Gap */
    {0x171d, 1, slave_6_pdo_entries + 18}, /* Gap */
    {0x171e, 1, slave_6_pdo_entries + 19}, /* Gap */
    {0x1702, 1, slave_6_pdo_entries + 20}, /* StartTimeNextOutput */
};

ec_sync_info_t slave_6_syncs[] = {
    {0, EC_DIR_OUTPUT, 10, slave_6_pdos + 0, EC_WD_ENABLE},
    {1, EC_DIR_OUTPUT, 10, slave_6_pdos + 10, EC_WD_ENABLE},
    {2, EC_DIR_INPUT, 1, slave_6_pdos + 20, EC_WD_DISABLE},
    {0xff}
};
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.etherlab.org/pipermail/etherlab-users/attachments/20110613/29f1ce6e/attachment-0002.htm>