diff --git a/stabilizer.py b/stabilizer.py
new file mode 100644
index 0000000..256b6e6
--- /dev/null
+++ b/stabilizer.py
@@ -0,0 +1,104 @@
+import json
+import asyncio
+from collections import OrderedDict
+import logging
+
+import numpy as np
+
+logger = logging.getLogger()
+
+
+class StabilizerError(Exception):
+    pass
+
+
+class StabilizerConfig:
+    async def connect(self, host, port=1235):
+        self.reader, self.writer = await asyncio.open_connection(host, port)
+
+    async def set(self, channel, iir):
+        up = OrderedDict([("channel", channel), ("iir", iir.as_dict())])
+        s = json.dumps(up, separators=(",", ":"))
+        assert "\n" not in s
+        logger.debug("send %s", s)
+        self.writer.write(s.encode() + b"\n")
+        r = (await self.reader.readline()).decode()
+        logger.debug("recv %s", r)
+        ret = json.loads(r, object_pairs_hook=OrderedDict)
+        if ret["code"] != 200:
+            raise StabilizerError(ret)
+        return ret
+
+
+class IIR:
+    t_update = 2e-6
+
+    def __init__(self):
+        self.ba = np.zeros(5, np.float32)
+        self.y_offset = 0.
+        self.y_min = -float(1 << 15)
+        self.y_max = float(1 << 15) - 1
+
+    def as_dict(self):
+        iir = OrderedDict()
+        iir["ba"] = [float(_) for _ in self.ba]
+        iir["y_offset"] = self.y_offset
+        iir["y_min"] = self.y_min
+        iir["y_max"] = self.y_max
+        return iir
+
+    def configure_pi(self, kp, ki, g=0.):
+        ki = np.copysign(ki, kp)*self.t_update*2
+        g = np.copysign(g, kp)
+        eps = np.finfo(np.float32).eps
+        if abs(ki) < eps:
+            a1, b0, b1 = 0., kp, 0.
+        else:
+            if abs(g) < eps:
+                c = 1.
+            else:
+                c = 1./(1. + ki/g)
+            a1 = 2*c - 1.
+            b0 = ki*c + kp
+            b1 = ki*c - a1*kp
+            if abs(b0 + b1) < eps:
+                raise ValueError("low integrator gain and/or gain limit")
+        self.ba[0] = b0
+        self.ba[1] = b1
+        self.ba[2] = 0.
+        self.ba[3] = a1
+        self.ba[4] = 0.
+
+    def set_x_offset(self, o):
+        b = self.ba[:3].sum()
+        self.y_offset = b*o
+
+
+if __name__ == "__main__":
+    import argparse
+    p = argparse.ArgumentParser()
+    p.add_argument("-s", "--stabilizer", default="10.0.16.99")
+    p.add_argument("-c", "--channel", default=0, type=int,
+                   help="Stabilizer channel to configure")
+    p.add_argument("-o", "--offset", default=0., type=float,
+                   help="X offset, in ADC LSB")
+    p.add_argument("-p", "--proportional-gain", default=1., type=float,
+                   help="Proportional gain, in DAC LSB/ADC LSB")
+    p.add_argument("-i", "--integral-gain", default=0., type=float,
+                   help="Integral gain, in DAC LSB/(ADC LSB*s)")
+
+    args = p.parse_args()
+
+    loop = asyncio.get_event_loop()
+    # loop.set_debug(True)
+    logging.basicConfig(level=logging.DEBUG)
+
+    async def main():
+        i = IIR()
+        i.configure_pi(args.proportional_gain, args.integral_gain)
+        i.set_x_offset(args.offset)
+        s = StabilizerConfig()
+        await s.connect(args.stabilizer)
+        r = await s.set(0, i)
+
+    loop.run_until_complete(main())