diff --git a/setup.cfg b/setup.cfg
index 1bd851a..5c2a17f 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -19,6 +19,7 @@ install_requires =
     moku>=3.0.0
     h5py
     pyyaml
+    pyserial
 python_requires = >=3.6
 include_package_data = True
 package_dir =
diff --git a/src/splendaq/__init__.py b/src/splendaq/__init__.py
index 311874f..ac38395 100644
--- a/src/splendaq/__init__.py
+++ b/src/splendaq/__init__.py
@@ -1,3 +1,4 @@
 from ._version import version as __version__
 from . import io
 from . import daq
+from . import control
diff --git a/src/splendaq/control/__init__.py b/src/splendaq/control/__init__.py
new file mode 100644
index 0000000..7bec055
--- /dev/null
+++ b/src/splendaq/control/__init__.py
@@ -0,0 +1,2 @@
+from ._hps import *
+from ._sr560 import *
diff --git a/src/splendaq/control/_hps.py b/src/splendaq/control/_hps.py
new file mode 100644
index 0000000..4a00fb7
--- /dev/null
+++ b/src/splendaq/control/_hps.py
@@ -0,0 +1,237 @@
+import serial
+
+__all__ = [
+    "HarvardPowerSupply",
+]
+
+class HarvardPowerSupply(object):
+    """
+    Class for controlling the Harvard Power Supply at the SLAC
+    SPLENDOR lab.
+
+    Notes
+    -----
+    The documentation of the power supply can be found here
+    https://wiki.harvard.edu/confluence/display/ESHOP/TT075%3A+Stanford+HEMT+supply
+
+    The serial commands are reprinted below in case the above link no
+    longer works, or the use has no access.
+
+    Commands:
+
+    S <arg>;  selects active slot.  Valid arguments are 1 and 2.
+        Power-on default is 1.
+    C <arg>; selects active HEMT channel.  Valid arguments are 1 and 2.
+        Power-on default is 1.
+    D <arg>; sets drain voltage of active HEMT channel in millivolts.
+        Valid arguments are floats in the range of 0.0 to 4990.0.
+    d; reads back drain voltage of selected HEMT channel.  Note that
+        this is mostly for diagnostics, as the "D" command is at least
+        as accurate as the "d" command.
+    r; reads back remote voltage (Vds+ - Vds-) of selected HEMT channel.
+        Mostly for diagnostics unless you anticipate significant
+        resistance on the Vds line to the HEMT.
+    G <arg>; sets the Vgs in millivolts. Valid arguments are in the
+        range of -5000.0 mV to +5000.0 mV.   Power-on default sets Vgs
+        to 0.0V.
+    g; reads back the previously set Gate voltage.  This is a
+        firmware-only operation, simply returning the previously set
+        Vgs, rather than measuring it.
+    N; turns oN the Vds driver of both HEMTs of the active slot.
+        Power-on default has the drivers turned off .
+    F; turns ofF the Vds driver of both HEMTs of the active slot.
+    i; returns the drain current of the selected HEMT, in mA.
+
+    The preferred protocol is to use "D" to set the correct Vds,
+    then use "N" to enable the output drivers.
+
+    """
+
+    def __init__(self, port):
+        """
+        Initialization of the HarvardPowerSupply class. Establishes
+        a connection to a specified port.
+
+        Parameters
+        ----------
+        port : str
+            The port to connect to that the HarvardPowerSupply is on,
+            e.g. "COM4".
+
+        """
+
+        self._HPS = serial.Serial()
+        self._HPS.port = port
+        self._HPS.open()
+        self.nslots = 2
+        self.nhemts = 2
+
+    def choose_slot(self, slot):
+        """
+        Choose which slot to control.
+
+        Parameters
+        ----------
+        slot : int
+            The slot to connect to, should be 1 or 2.
+
+        Returns
+        -------
+        slot_val : int
+            The value of the slot that was set.
+
+        """
+
+        self._HPS.write(f"S{slot};".encode())
+        slot_str = self._HPS.read_until(b"!")
+        self._HPS.write(b'N;')
+        self._HPS.read_until(b'!')
+        return int(slot_str[1:-1])
+
+    def choose_hemt(self, hemt):
+        """
+        Choose which HEMT to control on the specified slot.
+
+        Parameters
+        ----------
+        hemt : int
+            The HEMT to connect to on the previously specified slot,
+            should be 1 or 2.
+
+        Returns
+        -------
+        hemt_val : int
+            The value of the HEMT that was set.
+
+        """
+
+        self._HPS.write(f'C{hemt};'.encode())
+        return int(self._HPS.read_until(b'!')[1:-1])
+
+    def set_gate_voltage(self, value):
+        """
+        With HEMT and slot chosen, set the gate voltage on the HEMT.
+
+        Parameters
+        ----------
+        value : float
+            The gate voltage to be set for the HEMT, in mV. Allowed
+            values are -5000.0 to 5000.0, power-on defaults to 0.
+
+        Returns
+        -------
+        voltage_val : float
+            The value of the gate voltage that was set, in mV.
+
+        """
+
+        self._HPS.write(f"G{value};".encode())
+        return float(self._HPS.read_until(b'!')[1:-1])
+
+    def read_gate_voltage(self):
+        """
+        With HEMT and slot chosen, read the gate voltage on the HEMT.
+
+        Returns
+        -------
+        voltage_val : float
+            The value of the gate voltage that was set, in mV.
+
+        """
+
+        self._HPS.write(b"g;")
+        return float(self._HPS.read_until(b'!')[1:-1])
+
+    def set_drain_voltage(self, value):
+        """
+        With HEMT and slot chosen, set the drain voltage on the HEMT.
+
+        Parameters
+        ----------
+        value : float
+            The drain voltage to be set for the HEMT, in mV. Allowed
+            values are 0.0 to 4990.0.
+
+        Returns
+        -------
+        voltage_val : float
+            The value of the gate voltage that was set, in mV.
+
+        """
+
+        self._HPS.write(f"D{value};".encode())
+        return float(self._HPS.read_until(b'!')[1:-1])
+    
+    def read_drain_voltage(self):
+        """
+        With HEMT and slot chosen, read the drain voltage on the HEMT.
+
+        Returns
+        -------
+        voltage_val : float
+            The value of the drain voltage that was set, in mV.
+
+        """
+
+        self._HPS.write(b"d;")
+        return float(self._HPS.read_until(b'!')[1:-1])
+
+    def read_remote_voltage(self):
+        """
+        With HEMT and slot chosen, read the remote voltage
+        (Vds+ - Vds-) on the HEMT.
+
+        Returns
+        -------
+        voltage_val : float
+            The value of the remote voltage in mV.
+
+        """
+
+        self._HPS.write(b"d;")
+        return float(self._HPS.read_until(b'!')[1:-1])
+
+    def read_drain_current(self):
+        """
+        With HEMT and slot chosen, read the drain current on the HEMT.
+
+        Returns
+        -------
+        current_val : float
+            The value of the drain current in mA.
+
+        """
+
+        self._HPS.write(b"i;")
+        return float(self._HPS.read_until(b'!')[1:-1])
+    
+    def zero_all(self):
+        """
+        Function to zero all voltages, good to run at beginning and end
+        of running to ensure voltages are zero and the environment is
+        known.
+
+        Returns
+        -------
+        None
+
+        """
+
+        for slot in range(1, self.nslots + 1):
+            self.choose_slot(slot)
+            for hemt in range(1, self.nhemts + 1):
+                self.choose_hemt(hemt)
+                self.set_gate_voltage(0)
+                self.set_drain_voltage(0)
+
+    def close(self):
+        """
+        Close connection to the port to free it for other users.
+
+        Returns
+        -------
+        None
+
+        """
+
+        self._HPS.close()
diff --git a/src/splendaq/control/_sr560.py b/src/splendaq/control/_sr560.py
new file mode 100644
index 0000000..cb905a2
--- /dev/null
+++ b/src/splendaq/control/_sr560.py
@@ -0,0 +1,393 @@
+import numpy as np
+import serial
+
+
+__all__ = [
+    "SR560",
+]
+
+
+class SR560(object):
+    """
+    Class for controlling an SRS SR560 low-noise preamplifier.
+    Documentation on the various commands can be found in the SR560
+    user manual.
+    
+    """
+    
+    def __init__(self, port):
+        """
+        Initialization of the SS560 class. Establishes a connection to
+        a specified port.
+
+        Parameters
+        ----------
+        port : str
+            The port to connect to that the SR560 is on,
+            e.g. "COM4".
+
+        Returns
+        -------
+        None
+
+        """
+
+        self._SRS = serial.Serial()
+        self._SRS.port = port
+        self._SRS.open()
+
+    def set_coupling(self, value):
+        """
+        Set the coupling of the SR560.
+
+        Parameters
+        ----------
+        value : int
+            Sets the input coupling. Coupling to ground is 0,
+            DC coupling is 1, and AC coupling is 2.
+
+        Returns
+        -------
+        None
+
+        """
+
+        self._SRS.write(f"CPLG{value}\r\n".encode())
+
+    def set_dynamic_reserve(self, value):
+        """
+        Set the dynamic reserve of the SR560.
+
+        Parameters
+        ----------
+        value : int
+            Sets the dynamic reserve (DR). Low noise is 0,
+            high DR is 1, and calibration gains is 2.
+
+        Returns
+        -------
+        None
+
+        """
+
+        self._SRS.write(f"DYNR{value}\r\n".encode())
+
+    def set_blanking(self, value):
+        """
+        Operates amplifier blanking.
+
+        Parameters
+        ----------
+        value : int
+            Set 0 to for not blanked. Set to 1 for blanked.
+
+        Returns
+        -------
+        None
+
+        """
+
+        self._SRS.write(f"BLINK{value}\r\n".encode())
+
+    def set_filter_mode(self, value):
+        """
+        Sets filter mode.
+
+        Parameters
+        ----------
+        value : int
+            The filter mode to set, values below
+            0 = bypass
+            1 =  6 dB lowpass
+            2 = 12 dB lowpass
+            3 =  6 dB highpass
+            4 = 12 dB highpass
+            5 = bandpass
+
+        Returns
+        -------
+        None
+
+        """
+
+        self._SRS.write(f"FLTM{value}\r\n".encode())
+        
+    def set_gain(self, gain):
+        """
+        Controls the gain of the SR560.
+        
+        Parameters
+        ----------
+        gain : int
+            Sets the gain of the device, allowed values are
+            1 to 50000 in 1-2-5 sequence.
+
+        Returns
+        -------
+        None
+
+        """
+
+        gain_dict = {
+            1 : 0,
+            2 : 1,
+            5 : 2,
+            10 : 3,
+            20 : 4,
+            50 : 5,
+            100 : 6,
+            200 : 7,
+            500 : 8,
+            1000 : 9,
+            2000 : 10,
+            5000 : 11,
+            10000 : 12,
+            20000 : 13,
+            50000 : 14,
+        }
+
+        if gain not in gain_dict:
+            raise ValueError(
+                "Not a valid gain, see docstring for allowed values."
+            )
+
+        value = gain_dict[gain]
+        self._SRS.write(f"GAIN{value}\r\n".encode())
+
+    def set_highpass_filter(self, freq):
+        """
+        Set the highpass filter frequency.
+
+        Parameters
+        ----------
+        freq : float
+            The highpass filter frequency to be set. Defined in steps
+            from 0.03, 0.1, 0.3, 1, ..., 10000 Hz.
+
+        Returns
+        -------
+        None
+
+        """
+
+        freq_dict = {
+            0.03 : 0,
+            0.1 : 1,
+            0.3 : 2,
+            1 : 3,
+            3 : 4,
+            10 : 5,
+            30 : 6,
+            100 : 7,
+            300 : 8,
+            1000 : 9,
+            3000 : 10,
+            10000 : 11,
+        }
+
+        if freq not in freq_dict:
+            raise ValueError(
+                "Not a valid highpass freq, "
+                "see docstring for allowed values."
+            )
+
+        value = freq_dict[freq]
+        self._SRS.write(f"HFRQ{value}\r\n".encode())
+
+    def set_signal_invert(self, value):
+        """
+        Sets the signal invert status.
+
+        Parameters
+        ----------
+        value : int
+            0 is noninverted. 1 is inverted.
+
+        Returns
+        -------
+        None
+
+        """
+
+        self._SRS.write(f"INVT{value}\r\n".encode())
+
+    def listen_all(self):
+        """
+        Makes all attached SR560s listeners.
+
+        Returns
+        -------
+        None
+
+        """
+
+        self._SRS.write(b"LALL\r\n")
+
+    def listen(self, value):
+        """
+        Listen to a specific SR560.
+
+        Parameters
+        ----------
+        value : int
+            Makes SR560 with address `value` a listener.
+            Can be 0, 1, 2, or 3.
+
+        Returns
+        -------
+        None
+
+        """
+
+        self._SRS.write(f"LISN{value}\r\n".encode())
+
+    def set_lowpass_filter(self, freq):
+        """
+        Set the lowpass filter frequency.
+
+        Parameters
+        ----------
+        freq : float
+            The lowpass filter frequency to be set. Defined in steps
+            from 0.03, 0.1, 0.3, 1, ..., 1000000 Hz.
+
+        Returns
+        -------
+        None
+
+        """
+
+        freq_dict = {
+            0.03 : 0,
+            0.1 : 1,
+            0.3 : 2,
+            1 : 3,
+            3 : 4,
+            10 : 5,
+            30 : 6,
+            100 : 7,
+            300 : 8,
+            1000 : 9,
+            3000 : 10,
+            10000 : 11,
+            30000 : 12,
+            100000 : 13,
+            300000 : 14,
+            1000000 : 15,
+        }
+
+        if freq not in freq_dict:
+            raise ValueError(
+                "Not a valid lowpass freq, "
+                "see docstring for allowed values."
+            )
+
+        value = freq_dict[freq]
+        self._SRS.write(f"LFRQ{freq}\r\n".encode())
+
+    def reset_overload(self):
+        """
+        Resets overload for 0.5 seconds.
+
+        Returns
+        -------
+        None
+
+        """
+
+        self._SRS.write(b"ROLD\r\n")
+
+    def set_input_source(self, value):
+        """
+        Sets the input source.
+
+        Parameters
+        ----------
+        value : int
+            Input source. Set 0 for "A",
+            set to 1 for "A-B", and set to 2 for "B".
+
+        Returns
+        -------
+        None
+
+        """
+
+        self._SRS.write(f"SRCE{value}\r\n".encode())
+
+    def set_vernier_gain_status(self, value):
+        """
+        Set the vernier gain status.
+
+        Parameters
+        ----------
+        value : int
+            Set to 0 for cal'd gain. Set to 1 for vernier gain.
+
+        Returns
+        -------
+        None
+
+        """
+
+        self._SRS.write(f"UCAL{value}\r\n".encode())
+
+    def set_vernier_gain(self, gain):
+        """
+        Set the vernier gain on the SR560.
+
+        Parameters
+        ----------
+        gain : float
+            Set the vernier gain in 0.5% steps from 0 to 100.
+
+        Returns
+        -------
+        None
+
+        """
+        
+        allowed_vals = np.linspace(0, 100, num=201)
+
+        if gain not in allowed_vals:
+            raise ValueError(
+                "Vernier gain must be between 0 and 100 in steps of 0.5."
+            )
+
+        self._SRS.write(f"UCGN{gain}\r\n".encode())
+
+    def unlisten_all(self):
+        """
+        Unlisten. Unaddresses all attached SR560s.
+
+        Returns
+        -------
+        None
+
+        """
+
+        self._SRS.write(b"UNLS\r\n")
+
+    def reset_to_defaults(self):
+        """
+        Reset. Recalls default settings.
+
+        Returns
+        -------
+        None
+
+        """
+
+        self._SRS.write(b"*RST\r\n")
+
+    def close(self):
+        """
+        Close connection to the port to free it for other users.
+
+        Returns
+        -------
+        None
+
+        """
+        
+        self._SRS.close()