diff --git a/eiger/test/trimbit.py b/eiger/test/trimbit.py
new file mode 100644
index 0000000..1e0d397
--- /dev/null
+++ b/eiger/test/trimbit.py
@@ -0,0 +1,26 @@
+import matplotlib.pyplot as plt
+import numpy as np
+plt.ion()
+
+
+# These are more or less standard dacs, if you see strange effects
+# you might need to tune them 
+dacs = np.array([   0, 2480, 2900, 1400, 4000, 2556,  898,  848,    0,  855, 1100,
+       1100,  982,  895, 2000, 1550,  570,    0], dtype=np.int32)
+
+tb = np.zeros((256,1024), dtype = np.int32)
+
+# Create the desired pattern 
+for row in range(0,256,64):
+    for col in range(0,1024,64):
+        print(f'{row}, {col}')
+        tb[row:row+32, col:col+32] = 63
+
+
+fig, ax = plt.subplots()
+im = ax.imshow(tb)
+
+
+with open('trimbits.sn000', 'wb') as f:
+    dacs.tofile(f)
+    tb.tofile(f)
\ No newline at end of file
diff --git a/eiger/test/trimbits.sn000 b/eiger/test/trimbits.sn000
new file mode 100644
index 0000000..00b968b
Binary files /dev/null and b/eiger/test/trimbits.sn000 differ
diff --git a/eiger/xbl-daq-28/start_udp_chain.sh b/eiger/xbl-daq-28/start_udp_chain.sh
new file mode 100644
index 0000000..74da1ef
--- /dev/null
+++ b/eiger/xbl-daq-28/start_udp_chain.sh
@@ -0,0 +1,96 @@
+#!/bin/bash
+
+# path to build dir
+BUILD_PATH='/home/dbe/git/sf_daq_buffer/build/'
+# executables
+UDP_RECV='std_udp_recv'
+UDP_SYNC='std_udp_sync'
+EIGER_ASSEMBLER='eiger_assembler'
+
+# default config file
+# CONFIG_FILE='/home/dbe/git/sf_daq_buffer/eiger/xbl-daq-28/eiger-5M.json'
+CONFIG_FILE='/home/dbe/git/sf_daq_buffer/eiger/xbl-daq-28/eiger-1M.json'
+
+HELP_FLAG=0
+BIT_DEPTH=16
+while getopts n:h:u:c:b: flag
+do
+    case "${flag}" in
+        h ) HELP_FLAG=${OPTARG};;
+        c ) CONFIG_FILE=${OPTARG};;
+        b ) BIT_DEPTH=${OPTARG};;
+    esac
+done
+
+
+N_UDP_RECVS="`cat ${CONFIG_FILE} | grep -P '"n_modules":' | grep -o '[0-9]\+'`"
+
+
+# prints help and exits
+if (( ${HELP_FLAG} == 1 )); then
+    echo "Usage : $0 -n <n_udp_recvs> -c <compile_flag> -h <help_flag> -u <udp_executable> -c <config_file> -b <bit_depth>"
+    echo "           n_udp_recvs : number of receivers."
+    echo "           help_flag : show this help and exits."
+    echo "           config_file : detector configuration file."
+    echo "           bit_depth : detector bit depth."
+    exit
+fi
+
+# Start the receivers
+echo "Starting ${N_UDP_RECVS} udp receivers..."
+COUNTER=0
+if [ -f "${UDP_RECV}" ]; then
+    if [ -f "${CONFIG_FILE}" ]; then
+         while [  $COUNTER -lt ${N_UDP_RECVS} ]; do
+            "${BUILD_PATH}${UDP_RECV} ${CONFIG_FILE} ${COUNTER} ${BIT_DEPTH}" &
+            let COUNTER=COUNTER+1 
+            sleep 0.5
+         done
+    else
+        echo "Something went wrong while starting the ${UDP_RECV}..."
+        exit
+    fi
+else
+    echo "Error: ${UDP_RECV} wasn't found..."
+    exit
+fi
+
+
+# Start the std-udp-sync
+echo "Starting the ${UDP_SYNC}..."
+COUNTER=0
+if [ -f "${UDP_SYNC}" ]; then
+    if [ -f "${CONFIG_FILE}" ]; then
+        if [ ${BIT_DEPTH} -ne 0 ]; then
+            "${BUILD_PATH}${UDP_SYNC} ${CONFIG_FILE} ${BIT_DEPTH}" &
+            sleep 0.5
+        else
+            echo "Error: ${BIT_DEPTH} can't be zero..."
+            exit
+        fi
+        
+    else
+        echo "Something went wrong while starting the ${UDP_SYNC}..."
+        exit
+    fi
+else
+    echo "Error: ${UDP_SYNC} wasn't found..."
+    exit
+fi
+
+
+# Start the eiger assembler
+echo "Starting the ${EIGER_ASSEMBLER}..."
+COUNTER=0
+if [ -f "${EIGER_ASSEMBLER}" ]; then
+    if [ -f "${CONFIG_FILE}" ]; then
+        "${BUILD_PATH}${EIGER_ASSEMBLER} ${CONFIG_FILE} ${BIT_DEPTH}" &
+        sleep 0.5
+    else
+        echo "Something went wrong while starting the ${EIGER_ASSEMBLER}..."
+        exit
+    fi
+else
+    echo "Error: ${EIGER_ASSEMBLER} wasn't found..."
+    exit
+fi
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