diff --git a/light9/collector/service.py b/light9/collector/service.py
--- a/light9/collector/service.py
+++ b/light9/collector/service.py
@@ -9,6 +9,7 @@ Input can be over http or zmq.
 import asyncio
 import functools
 import logging
+import subprocess
 import traceback
 from typing import List
 
@@ -35,6 +36,7 @@ import zmq.asyncio
 
 STAT_SETATTR = Summary('set_attr', 'setAttr calls')
 
+# this is the rate sent to usb
 RATE = 20
 
 
@@ -91,6 +93,14 @@ async def zmqListener(collector):
         traceback.print_exc()
         raise
 
+def findDevice():
+    for line in subprocess.check_output("lsusb").decode('utf8').splitlines():
+        if '16c0:05dc' in line:
+            words = line.split(':')[0].split()
+            dev = f'/dev/bus/usb/{words[1]}/{words[3]}'
+            log.info(f'device will be {dev}')
+            return dev ,int(words[3])
+    raise ValueError("no matching uDMX found")
 
 def main():
     logging.getLogger('autodepgraphapi').setLevel(logging.INFO)
@@ -99,16 +109,17 @@ def main():
 
     graph = SyncedGraph(networking.rdfdb.url, "collector")
 
+    devPath, usbAddress = findDevice()
+            # if user doesn't have r/w, fail now
     try:
         # todo: drive outputs with config files
-        rate = 30
         outputs: List[Output] = [
             # ArtnetDmx(L9['output/dmxA/'],
             #           host='127.0.0.1',
             #           port=6445,
             #           rate=rate),
             #sudo chmod a+rw /dev/bus/usb/003/021
-            Udmx(L9['output/dmxA/'], bus=3, address=21, lastDmxChannel=200, rate=RATE),
+            Udmx(L9['output/dmxA/'], bus=1, address=usbAddress, lastDmxChannel=200, rate=RATE),
         ]
     except Exception:
         log.error("setting up outputs:")