diff --git a/plot_sayma_data.py b/plot_sayma_data.py
index 966605e..d40619d 100644
--- a/plot_sayma_data.py
+++ b/plot_sayma_data.py
@@ -3,6 +3,7 @@ import matplotlib.pyplot as plot
 from scipy import signal, constants
 import argparse
 import os
+import datetime
 
 
 def rp_raw_to_numpy(rp_raw):
@@ -38,11 +39,15 @@ def main():
         raise ValueError("Both files are the same.")
 
     with open(os.path.join(args.dir, y1_filename), 'rb') as f:
-        y1_raw = f.read().decode('utf-8')
+        y1_now_iso, y1_raw = [l.decode('utf-8') for l in f.readlines()]
     with open(os.path.join(args.dir, y2_filename), 'rb') as f:
-        y2_raw = f.read().decode('utf-8')
+        y2_now_iso, y2_raw = [l.decode('utf-8') for l in f.readlines()]
     if None in [y1_raw, y2_raw]:
         raise IOError("Raw RP string files cannot be opened.")
+    if y1_now_iso != y2_now_iso:
+        raise ValueError("Timestamps of raw RP files are not identical.")
+    now_iso = y1_now_iso.rstrip()
+    print("Reading raw RP data collected at {}.".format(now_iso))
 
     y1 = rp_raw_to_numpy(y1_raw)
     y2 = rp_raw_to_numpy(y2_raw)
diff --git a/rp_get_sayma_data.py b/rp_get_sayma_data.py
index 95f2cdd..51e3f1c 100644
--- a/rp_get_sayma_data.py
+++ b/rp_get_sayma_data.py
@@ -2,6 +2,7 @@ import socket
 import asyncio
 import argparse
 import os
+import datetime
 
 
 class RPSCPI:
@@ -57,6 +58,12 @@ async def gather_trigger(rp_list):
 
 
 def main():
+    # Get timestamp at script start
+    now = datetime.datetime.now().replace(
+        microsecond=0,  # get rid of microseconds when printed
+    )
+    now_iso = now.isoformat(sep=' ')
+
     parser = argparse.ArgumentParser(description="Data collection tool for Sayma DAC/TTL at RedPitaya")
     parser.add_argument("dir", help="output directory", type=str)
     parser.add_argument("rps_gains", metavar="RP_NAME:CH1_GAIN,CH2_GAIN",
@@ -95,11 +102,14 @@ def main():
         for rp in rps:
             y1_raw = rp.get_data(1)
             y2_raw = rp.get_data(2)
+            print("Data collection started at {}.".format(now_iso))
 
             with open(os.path.join(args.dir, 'rp_{}_y1_raw.bin'.format(rp.name)), 'wb') as f:
+                f.write("{}\n".format(now_iso).encode('utf-8'))
                 f.write(y1_raw.encode('utf-8'))
                 print("Succesfully written y1 raw data from RP {}.".format(rp.name))
             with open(os.path.join(args.dir, 'rp_{}_y2_raw.bin'.format(rp.name)), 'wb') as f:
+                f.write("{}\n".format(now_iso).encode('utf-8'))
                 f.write(y2_raw.encode('utf-8'))
                 print("Succesfully written y2 raw data from RP {}.".format(rp.name))