[etherlab-users] Datagram Timeout and other issues
Newell Jensen
pillar2012 at gmail.com
Tue Nov 23 18:34:22 CET 2010
Andreas,
Here is the output from:
1. $ ethercat slaves -v
=== Master 0, Slave 0 ===
State: PREOP
Flag: +
Identity:
Vendor Id: 0x00000002
Product code: 0x044c2c52
Revision number: 0x00110000
Serial number: 0x00000000
DL information:
FMMU bit operation: no
Distributed clocks: yes, 64 bit
DC system time transmission delay: 0 ns
Port Type Link Loop Signal NextSlave RxTime [ns] Diff [ns] NextDc
[ns]
0 MII up open yes - 2549051802
0 0
1 EBUS up open yes 1 2549052242 440
220
2 MII down closed no - -
- -
3 N/A down closed no - -
- -
General:
Group: SystemBk
Image name:
Order number: EK1100
Device name: EK1100 EtherCAT-Koppler (2A E-Bus)
Flags:
Enable SafeOp: no
Enable notLRW: no
Current consumption: -2000 mA
=== Master 0, Slave 1 ===
State: PREOP
Flag: +
Identity:
Vendor Id: 0x00000002
Product code: 0x07d43052
Revision number: 0x00100000
Serial number: 0x00000000
DL information:
FMMU bit operation: no
Distributed clocks: yes, 64 bit
DC system time transmission delay: 220 ns
Port Type Link Loop Signal NextSlave RxTime [ns] Diff [ns] NextDc
[ns]
0 EBUS up open yes 0 2549892332 0
220
1 EBUS up open yes - 2549892482
150 0
2 N/A down closed no - -
- -
3 N/C down closed no - -
- -
General:
Group: DigOut
Image name: TERM_DO
Order number: EL2004
Device name: EL2004 4K. Dig. Ausgang 24V, 0.5A
Flags:
Enable SafeOp: no
Enable notLRW: no
Current consumption: 100 mA
2. $ ethercat master -v
Master0
Phase: Idle
Active: no
Slaves: 2
Ethernet devices:
Main: 00:04:5f:b0:8e:49 (attached)
Link: UP
Tx frames: 126992
Rx frames: 126991
Lost frames: 0
Tx bytes: 7619664
Tx errors: 0
Tx frame rate [1/s]: 525 542 534
Tx rate [KByte/s]: 30.8 31.8 31.3
Loss rate [1/s]: 0 0 0
Frame loss [%]: 0.0 0.0 0.0
Backup: None.
Distributed clocks:
Reference clock: Slave 0
Application time: 0
2000-01-01 00:00:00.000000000
3. And here is my code (I just modified the user example main.c a bit):
/*****************************************************************************
*
* $Id$
*
* Copyright (C) 2007-2009 Florian Pose, Ingenieurgemeinschaft IgH
*
* This file is part of the IgH EtherCAT Master.
*
* The IgH EtherCAT Master is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version 2,
as
* published by the Free Software Foundation.
*
* The IgH EtherCAT Master is distributed in the hope that it will be
useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General
* Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with the IgH EtherCAT Master; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
USA
*
* ---
*
* The license mentioned above concerns the source code only. Using the
* EtherCAT technology and brand is only permitted in compliance with the
* industrial property and similar rights of Beckhoff Automation GmbH.
*
****************************************************************************/
#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <string.h>
#include <sys/resource.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
/****************************************************************************/
#include "ecrt.h"
/****************************************************************************/
// Application parameters
#define FREQUENCY 100
#define PRIORITY 1
// Optional features
#define CONFIGURE_PDOS 1
#define SDO_ACCESS 0
/****************************************************************************/
// EtherCAT
static ec_master_t *master = NULL;
static ec_master_state_t master_state = {};
static ec_domain_t *domain1 = NULL;
static ec_domain_state_t domain1_state = {};
static ec_slave_config_t *sc_ana_in = NULL;
static ec_slave_config_state_t sc_ana_in_state = {};
// Timer
static unsigned int sig_alarms = 0;
static unsigned int user_alarms = 0;
/****************************************************************************/
// process data
static uint8_t *domain1_pd = NULL;
// nj -- this was found from command: $ ethercat slaves
#define BusCouplerPos 0, 0
#define DigOutSlavePos 0, 1
#define DigInSlavePos 0, 2
#define AnaOutSlavePos 0, 3
#define AnaInSlavePos 0, 4
// nj -- this was found from the command: $ ethercat slaves -v
// or it can be found when using ethercat cstruct option
#define Beckhoff_EK1100 0x00000002, 0x044c2c52 // bus coupler
#define Beckhoff_EL2004 0x00000002, 0x07d43052 // digital output
#define Beckhoff_EL1004 0x00000002, 0x03ec3052 // digital input
#define Beckhoff_EL4132 0x00000002, 0x10243052 // analog output
#define Beckhoff_EL3102 0x00000002, 0x0c1e3052 // analog input
// offsets for PDO entries
static unsigned int off_ana_in_status;
static unsigned int off_ana_in_value;
static unsigned int off_ana_out;
static unsigned int off_dig_out;
static unsigned int off_dig_in; // nj -- added
const static ec_pdo_entry_reg_t domain1_regs[] = {
{DigOutSlavePos, Beckhoff_EL2004, 0x7000, 1, &off_dig_out},
{DigInSlavePos, Beckhoff_EL1004, 0x6000, 1, &off_dig_in},
{AnaOutSlavePos, Beckhoff_EL4132, 0x3001, 1, &off_ana_out},
{AnaInSlavePos, Beckhoff_EL3102, 0x3101, 1, &off_ana_in_status},
{AnaInSlavePos, Beckhoff_EL3102, 0x3101, 2, &off_ana_in_value},
{}
};
static unsigned int counter = 0;
static unsigned int blink = 0;
/*****************************************************************************/
#if CONFIGURE_PDOS
// DIGITAL OUTPUT
/* Master 0, Slave 1, "EL2004"
* Vendor ID: 0x00000002
* Product code: 0x07d43052
* Revision number: 0x00100000
*/
ec_pdo_entry_info_t el2004_pdo_entries[] = {
{0x7000, 0x01, 1}, /* Output */
{0x7010, 0x01, 1}, /* Output */
{0x7020, 0x01, 1}, /* Output */
{0x7030, 0x01, 1}, /* Output */
};
ec_pdo_info_t el2004_pdos[] = {
{0x1600, 1, el2004_pdo_entries + 0}, /* Channel 1 */
{0x1601, 1, el2004_pdo_entries + 1}, /* Channel 2 */
{0x1602, 1, el2004_pdo_entries + 2}, /* Channel 3 */
{0x1603, 1, el2004_pdo_entries + 3}, /* Channel 4 */
};
ec_sync_info_t el2004_syncs[] = {
{0, EC_DIR_OUTPUT, 4, el2004_pdos + 0, EC_WD_ENABLE},
{0xff}
};
// DIGITAL INPUT
/* Master 0, Slave 2, "EL1004"
* Vendor ID: 0x00000002
* Product code: 0x03ec3052
* Revision number: 0x00100000
*/
ec_pdo_entry_info_t el1004_pdo_entries[] = {
{0x6000, 0x01, 1}, /* Input */
{0x6010, 0x01, 1}, /* Input */
{0x6020, 0x01, 1}, /* Input */
{0x6030, 0x01, 1}, /* Input */
};
ec_pdo_info_t el1004_pdos[] = {
{0x1a00, 1, el1004_pdo_entries + 0}, /* Channel 1 */
{0x1a01, 1, el1004_pdo_entries + 1}, /* Channel 2 */
{0x1a02, 1, el1004_pdo_entries + 2}, /* Channel 3 */
{0x1a03, 1, el1004_pdo_entries + 3}, /* Channel 4 */
};
ec_sync_info_t el1004_syncs[] = {
{0, EC_DIR_INPUT, 4, el1004_pdos + 0, EC_WD_DISABLE},
{0xff}
};
// ANALOG OUTPUT
/* Master 0, Slave 3, "EL4132"
* Vendor ID: 0x00000002
* Product code: 0x10243052
* Revision number: 0x00000000
*/
ec_pdo_entry_info_t el4132_pdo_entries[] = {
{0x3001, 0x01, 16}, /* Value */
{0x3002, 0x01, 16}, /* Value */
};
ec_pdo_info_t el4132_pdos[] = {
{0x1600, 1, el4132_pdo_entries + 0}, /* RxPDO 001 mapping */
{0x1601, 1, el4132_pdo_entries + 1}, /* RxPDO 002 mapping */
};
ec_sync_info_t el4132_syncs[] = {
{0, EC_DIR_OUTPUT, 0, NULL, EC_WD_DISABLE},
{1, EC_DIR_INPUT, 0, NULL, EC_WD_DISABLE},
{2, EC_DIR_OUTPUT, 2, el4132_pdos + 0, EC_WD_DISABLE},
{3, EC_DIR_INPUT, 0, NULL, EC_WD_DISABLE},
{0xff}
};
// ANALOG INPUT
/* Master 0, Slave 4, "EL3102"
* Vendor ID: 0x00000002
* Product code: 0x0c1e3052
* Revision number: 0x00000000
*/
ec_pdo_entry_info_t el3102_pdo_entries[] = {
{0x3101, 0x01, 8},
{0x3101, 0x02, 16},
{0x3102, 0x01, 8},
{0x3102, 0x02, 16},
};
ec_pdo_info_t el3102_pdos[] = {
{0x1a00, 2, el3102_pdo_entries + 0}, /* TxPDO 001 mapping */
{0x1a01, 2, el3102_pdo_entries + 2}, /* TxPDO 002 mapping */
};
ec_sync_info_t el3102_syncs[] = {
{0, EC_DIR_OUTPUT, 0, NULL, EC_WD_DISABLE},
{1, EC_DIR_INPUT, 0, NULL, EC_WD_DISABLE},
{2, EC_DIR_OUTPUT, 0, NULL, EC_WD_DISABLE},
{3, EC_DIR_INPUT, 2, el3102_pdos + 0, EC_WD_DISABLE},
{0xff}
};
#endif
/*****************************************************************************/
#if SDO_ACCESS
static ec_sdo_request_t *sdo;
#endif
/*****************************************************************************/
void check_domain1_state(void)
{
ec_domain_state_t ds;
ecrt_domain_state(domain1, &ds);
if (ds.working_counter != domain1_state.working_counter)
//printf("Domain1: WC %u.\n", ds.working_counter);
if (ds.wc_state != domain1_state.wc_state)
//printf("Domain1: State %u.\n", ds.wc_state);
domain1_state = ds;
}
/*****************************************************************************/
void check_master_state(void)
{
ec_master_state_t ms;
ecrt_master_state(master, &ms);
if (ms.slaves_responding != master_state.slaves_responding)
//printf("%u slave(s).\n", ms.slaves_responding);
if (ms.al_states != master_state.al_states)
//printf("AL states: 0x%02X.\n", ms.al_states);
if (ms.link_up != master_state.link_up)
//printf("Link is %s.\n", ms.link_up ? "up" : "down");
master_state = ms;
}
/*****************************************************************************/
void check_slave_config_states(void)
{
ec_slave_config_state_t s;
ecrt_slave_config_state(sc_ana_in, &s);
if (s.al_state != sc_ana_in_state.al_state)
//printf("AnaIn: State 0x%02X.\n", s.al_state);
if (s.online != sc_ana_in_state.online)
//printf("AnaIn: %s.\n", s.online ? "online" : "offline");
if (s.operational != sc_ana_in_state.operational)
//printf("AnaIn: %soperational.\n",
//s.operational ? "" : "Not ");
sc_ana_in_state = s;
}
/*****************************************************************************/
#if SDO_ACCESS
void read_sdo(void)
{
switch (ecrt_sdo_request_state(sdo)) {
case EC_REQUEST_UNUSED: // request was not used yet
ecrt_sdo_request_read(sdo); // trigger first read
break;
case EC_REQUEST_BUSY:
fprintf(stderr, "Still busy...\n");
break;
case EC_REQUEST_SUCCESS:
fprintf(stderr, "SDO value: 0x%04X\n",
EC_READ_U16(ecrt_sdo_request_data(sdo)));
ecrt_sdo_request_read(sdo); // trigger next read
break;
case EC_REQUEST_ERROR:
fprintf(stderr, "Failed to read SDO!\n");
ecrt_sdo_request_read(sdo); // retry reading
break;
}
}
#endif
/****************************************************************************/
void cyclic_task()
{
int i;
// receive process data
ecrt_master_receive(master);
ecrt_domain_process(domain1);
// check process data state (optional)
check_domain1_state();
/* if (counter) { */
/* counter--; */
/* } else { // do this at 1 Hz */
// counter = FREQUENCY;
// calculate new process data
blink = !blink;
// check for master state (optional)
//check_master_state();
// check for islave configuration state(s) (optional)
//check_slave_config_states();
#if SDO_ACCESS
// read process data SDO
read_sdo();
#endif
// }
#if 0
// read process data
printf("AnaIn: state %u value %u\n",
EC_READ_U8(domain1_pd + off_ana_in_status),
EC_READ_U16(domain1_pd + off_ana_in_value));
#endif
#if 1
// write process data
EC_WRITE_U8(domain1_pd + off_dig_out, blink ? 0x01 : 0x00);
#endif
// send process data
ecrt_domain_queue(domain1);
ecrt_master_send(master);
}
/****************************************************************************/
void signal_handler(int signum) {
switch (signum) {
case SIGALRM:
sig_alarms++;
break;
}
}
/****************************************************************************/
int main(int argc, char **argv)
{
ec_slave_config_t *sc;
struct sigaction sa;
struct itimerval tv;
master = ecrt_request_master(0);
if (!master)
return -1;
domain1 = ecrt_master_create_domain(master);
if (!domain1)
return -1;
if (!(sc_ana_in = ecrt_master_slave_config(
master, AnaInSlavePos, Beckhoff_EL3102))) {
fprintf(stderr, "Failed to get slave configuration.\n");
return -1;
}
#if SDO_ACCESS
fprintf(stderr, "Creating SDO requests...\n");
if (!(sdo = ecrt_slave_config_create_sdo_request(sc_ana_in, 0x3102, 2,
2))) {
fprintf(stderr, "Failed to create SDO request.\n");
return -1;
}
ecrt_sdo_request_timeout(sdo, 500); // ms
#endif
#if CONFIGURE_PDOS
printf("Configuring PDOs...\n");
if (ecrt_slave_config_pdos(sc_ana_in, EC_END, el3102_syncs)) {
fprintf(stderr, "Failed to configure PDOs (3102).\n");
return -1;
}
if (!(sc = ecrt_master_slave_config(
master, AnaOutSlavePos, Beckhoff_EL4132))) {
fprintf(stderr, "Failed to get slave configuration.\n");
return -1;
}
if (ecrt_slave_config_pdos(sc, EC_END, el4132_syncs)) {
fprintf(stderr, "Failed to configure PDOs (4132).\n");
return -1;
}
if (!(sc = ecrt_master_slave_config(
master, DigOutSlavePos, Beckhoff_EL2004))) {
fprintf(stderr, "Failed to get slave configuration.\n");
return -1;
}
if (ecrt_slave_config_pdos(sc, EC_END, el2004_syncs)) {
fprintf(stderr, "Failed to configure PDOs (2004).\n");
return -1;
}
if (!(sc = ecrt_master_slave_config(
master, DigInSlavePos, Beckhoff_EL1004))) {
fprintf(stderr, "Failed to get slave configuration.\n");
return -1;
}
if (ecrt_slave_config_pdos(sc, EC_END, el1004_syncs)) {
fprintf(stderr, "Failed to configure PDOs (1004).\n");
return -1;
}
#endif
// Create configuration for bus coupler
sc = ecrt_master_slave_config(master, BusCouplerPos, Beckhoff_EK1100);
if (!sc)
return -1;
if (ecrt_domain_reg_pdo_entry_list(domain1, domain1_regs)) {
fprintf(stderr, "PDO entry registration failed (EK1100)!\n");
return -1;
}
//printf("Activating master...\n");
if (ecrt_master_activate(master))
return -1;
if (!(domain1_pd = ecrt_domain_data(domain1))) {
return -1;
}
#if PRIORITY
pid_t pid = getpid();
if (setpriority(PRIO_PROCESS, pid, -19))
fprintf(stderr, "Warning: Failed to set priority: %s\n",
strerror(errno));
#endif
sa.sa_handler = signal_handler;
sigemptyset(&sa.sa_mask);
sa.sa_flags = 0;
if (sigaction(SIGALRM, &sa, 0)) {
fprintf(stderr, "Failed to install signal handler!\n");
return -1;
}
//printf("Starting timer...\n");
tv.it_interval.tv_sec = 0;
tv.it_interval.tv_usec = 250;//1000000 / FREQUENCY;
tv.it_value.tv_sec = 0;
tv.it_value.tv_usec = 1000;
if (setitimer(ITIMER_REAL, &tv, NULL)) {
fprintf(stderr, "Failed to start timer: %s\n", strerror(errno));
return 1;
}
while (1) {
pause();
#if 0
struct timeval t;
gettimeofday(&t, NULL);
printf("%u.%06u\n", t.tv_sec, t.tv_usec);
#endif
while (sig_alarms != user_alarms) {
cyclic_task();
user_alarms++;
}
}
return 0;
}
/****************************************************************************/
On Mon, Nov 22, 2010 at 11:43 PM, Andreas Stewering-Bone
<ab at igh-essen.com>wrote:
> Hello Newell,
>
> There seems to be a communication problem.
>
> can you reduce the slaves only using the EK1100 and the EL2004
>
> and post
>
> ethercat slaves -v
>
> and
>
> ethercat master -v
>
> and maybe your code
>
> Greatings
>
>
> Andreas
>
>
>
> Newell Jensen schrieb:
>
>> Hello All,
>>
>> I am in the middle of trying to test a simple cyclic loop that toggles the
>> digital output of the EL2004 which is attached to the EK1100. We have an
>> oscilloscope attached to this digital output so that we can verify the
>> square waveform that is created from the toggling of this digital output to
>> see how fast the system can respond. However, we are getting some bleeps in
>> this waveform and I believe they are coming from the following errors:
>>
>> [ 24.920744] EtherCAT: Accepting device 00:04:5F:B0:8E:49 for master 0.
>> [ 24.920924] ec_generic: Binding socket to interface 3 (eth1).
>> [ 24.930057] EtherCAT 0: Starting EtherCAT-IDLE thread.
>> [ 25.532553] e1000e: eth1 NIC Link is Up 100 Mbps Full Duplex, Flow
>> Control: None
>> [ 25.532724] 0000:02:00.0: eth1: 10/100 speed: disabling TSO
>> [ 25.533311] EtherCAT 0: Link state changed to UP.
>> [ 25.533401] ADDRCONF(NETDEV_CHANGE): eth1: link becomes ready
>> [ 25.535026] EtherCAT 0: 5 slave(s) responding.
>> [ 25.535160] EtherCAT 0: Slave states: PREOP.
>> [ 25.537370] EtherCAT 0: Scanning bus.
>> [ 27.158003] e1000e: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow
>> Control: RX/TX
>> [ 27.384322] EtherCAT WARNING 0: 1 datagram TIMED OUT!
>> [ 27.596617] EtherCAT ERROR 0-4: Reception of CoE upload request for SDO
>> 0x1c12:0 failed with timeout after 1000 ms: No response.
>> [ 27.596636] EtherCAT ERROR 0-4: Failed to read number of assigned PDOs
>> for SM2.
>> [ 28.596325] EtherCAT ERROR 0-4: Reception of CoE upload request for SDO
>> 0x1c13:0 failed with timeout after 1000 ms: No response.
>> [ 28.596344] EtherCAT ERROR 0-4: Failed to read number of assigned PDOs
>> for SM3.
>> [ 28.596355] EtherCAT 0: Bus scanning completed in 3061 ms.
>> [ 28.596364] EtherCAT ERROR 0: Failed to calculate bus topology.
>> [ 215.389287] EtherCAT WARNING 0: 1 datagram TIMED OUT!
>> [ 215.389324] EtherCAT WARNING 0: 1 datagram UNMATCHED!
>> [ 341.602318] EtherCAT WARNING 0: 1 datagram TIMED OUT!
>> [ 341.602339] EtherCAT WARNING 0: 1 datagram UNMATCHED!
>> [ 403.613306] EtherCAT WARNING 0: 1 datagram TIMED OUT!
>> [ 403.613369] EtherCAT WARNING 0: 1 datagram UNMATCHED!
>> [ 469.944365] EtherCAT WARNING 0: 1 datagram TIMED OUT!
>> [ 469.944387] EtherCAT WARNING 0: 1 datagram UNMATCHED!
>> [ 500.001363] EtherCAT WARNING 0: 1 datagram TIMED OUT!
>> [ 500.001384] EtherCAT WARNING 0: 1 datagram UNMATCHED!
>> [ 523.217296] EtherCAT WARNING 0: 2 datagrams TIMED OUT!
>> [ 523.217332] EtherCAT WARNING 0: 2 datagrams UNMATCHED!
>> [ 683.901311] EtherCAT WARNING 0: 1 datagram TIMED OUT!
>> [ 683.901395] EtherCAT WARNING 0: 1 datagram UNMATCHED!
>> [ 757.067347] EtherCAT WARNING 0: 1 datagram TIMED OUT!
>> [ 757.067368] EtherCAT WARNING 0: 1 datagram UNMATCHED!
>> [ 759.003291] EtherCAT WARNING 0: 1 datagram TIMED OUT!
>> [ 759.003331] EtherCAT WARNING 0: 1 datagram UNMATCHED!
>> [ 1060.422312] EtherCAT WARNING 0: 1 datagram TIMED OUT!
>> [ 1060.422370] EtherCAT WARNING 0: 1 datagram UNMATCHED!
>> [ 1492.539299] EtherCAT WARNING 0: 1 datagram TIMED OUT!
>> [ 1492.539339] EtherCAT WARNING 0: 1 datagram UNMATCHED!
>> [ 2260.018306] EtherCAT WARNING 0: 1 datagram TIMED OUT!
>> [ 2260.018364] EtherCAT WARNING 0: 1 datagram UNMATCHED!
>> [ 2435.205290] EtherCAT WARNING 0: 1 datagram TIMED OUT!
>> [ 2435.205325] EtherCAT WARNING 0: 1 datagram UNMATCHED!
>>
>>
>> Any one have any ideas how I can get rid of all these different errors?
>>
>> Plus, we are shooting for having a system that polls (cyclic task) at 0.5
>> ms (2 kHz) with a jitter of about 10 us and from everything that I have read
>> in the ethercat master documentation pdf...it seems like this should not be
>> a problem at all.
>>
>> My setup:
>> Linux ubuntu-ioc 2.6.31-11-rt #154-Ubuntu SMP PREEMPT RT Wed Jun 9
>> 12:28:53 UTC 2010 i686 GNU/Linux
>> generic driver
>> IgH EtherCAT master devel e9f722488fcd
>>
>> Thanks!
>>
>> --
>>
>> Newell
>>
>>
>> ------------------------------------------------------------------------
>>
>> _______________________________________________
>> etherlab-users mailing list
>> etherlab-users at etherlab.org
>> http://lists.etherlab.org/mailman/listinfo/etherlab-users
>>
>>
>
>
> --
>
> ------------------------------------------------------------------------
>
> Dipl.-Ing. Andreas Stewering-Bone Amtsgericht Essen HRB 11500
> Ingenieurgemeinschaft IgH USt-Id.-Nr.: DE 174 626 722
> Gesellschaft für Ingenieurleistungen mbH Geschäftsführung:
> Heinz-Bäcker-Str. 34 Dr.-Ing. S. Rotthäuser
> D-45356 Essen Dr.-Ing. T. Finke
> Tel.: +49 201 / 360-14-15 Dr.-Ing. W. Hagemeister
> Fax.: +49 201 / 360-14-14 Tel.: +49 201 / 360-14-0
> Andreas.Stewering-Bone at igh-essen.com http://www.igh-essen.com
> ------------------------------------------------------------------------
>
>
--
Newell
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.etherlab.org/pipermail/etherlab-users/attachments/20101123/b0ae51b8/attachment-0004.htm>
More information about the Etherlab-users
mailing list