Fixes.

coupler/opc-ua-server/coupler1.sh

 #!/bin/bash
 COUPLER_SR=.
-$COUPLER_SR/server -m 1 -b 1 -i 1 -l 2,3 -t 100 -o 10000
+$COUPLER_SR/server -m 1 -b 1 -i 1 -l 2 -t 1000 -o 5000 -n opc.udp://224.0.0.22:4840/

coupler/opc-ua-server/coupler2.sh

 #!/bin/bash
 COUPLER_SR=.
-$COUPLER_SR/server -p 4841 -m 1 -b 1 -i 2 -l 1,3 -t 100 -o 10000
+$COUPLER_SR/server -p 4841 -m 1 -b 1 -i 2 -l 1 -t 1000 -o 5000 -n opc.udp://224.0.0.22:4840/

coupler/opc-ua-server/coupler3.sh

 #!/bin/bash
 COUPLER_SR=.
-$COUPLER_SR/server -p 4842 -m 1 -b 1 -i 3 -l 1,2 -t 100 -o 10000
+$COUPLER_SR/server -p 4842 -m 1 -b 1 -i 3 -l 1,2 -t 1000 -o 5000

coupler/opc-ua-server/keep_alive.h

@@ -5,8 +5,8 @@ char *NETWORK_ADDRESS_URL_DATA_TYPE = "opc.udp://224.0.0.22:4840/";
 // global HEART BEATs of coupler
 static unsigned int HEART_BEATS = 0;
 
-// the heart beat interval$$
-const int DEFAULT_HEART_BEAT_INTERVAL = 10;
+// the heart beat interval (in ms)
+const int DEFAULT_HEART_BEAT_INTERVAL = 250;
 static int HEART_BEAT_INTERVAL = DEFAULT_HEART_BEAT_INTERVAL;
 
 // the timeout in millis after which a coupler is considered down