diff --git a/src/finesse/components/modal/workspace.pxd b/src/finesse/components/modal/workspace.pxd
index 116df61d1dc27e46d9e7ff72045bda3c3b495e08..83c5b778a5401fd761f3982ecb3e752c1928b8cf 100644
--- a/src/finesse/components/modal/workspace.pxd
+++ b/src/finesse/components/modal/workspace.pxd
@@ -1,8 +1,9 @@
 from finesse.components.workspace cimport ConnectorWorkspace
 from finesse.knm cimport KnmWorkspace
-from finesse.simulations.base cimport BaseSimulation, NodeBeamParam
-from finesse.cymath cimport complex_t
-
+from finesse.simulations.base cimport NodeBeamParam
+from finesse.simulations.basematrix cimport CarrierSignalMatrixSimulation
+from finesse.cymath.complex cimport complex_t, DenseZMatrix
+from cpython.ref cimport PyObject
 import numpy as np
 cimport numpy as np
 
@@ -24,6 +25,8 @@ cdef struct KnmInfo:
     double *beta_y
     double beta_y_factor
     double beta_x_factor
+    # Pointer to a KnmMatrix
+    DenseZMatrix *mtx
 
 cdef class KnmConnectorWorkspace(ConnectorWorkspace):
     # Sequence of string reprs of the optical couplings
diff --git a/src/finesse/components/modal/workspace.pyx b/src/finesse/components/modal/workspace.pyx
index 6d1a5a84a8e3395c6210ea33b99f0418b2d6cd78..1555b2e5ba44b7a4b4d89b2d98e6ab2edb8058a4 100644
--- a/src/finesse/components/modal/workspace.pyx
+++ b/src/finesse/components/modal/workspace.pyx
@@ -14,11 +14,12 @@ from finesse.knm cimport (
     compute_knm_matrix_bh,
     reverse_gouy_phases,
     zero_tem00_phase,
+    flip_odd_horizontal,
 )
 from finesse.cymath.gaussbeam cimport c_transform_q
 from finesse.components.workspace cimport ConnectorWorkspace
 from finesse.components.general import NodeType
-from finesse.simulations.base cimport BaseSimulation, NodeBeamParam
+from finesse.simulations.base cimport NodeBeamParam
 import finesse.components as components
 
 
@@ -56,9 +57,10 @@ cdef class KnmConnectorWorkspace(ConnectorWorkspace):
         pass
 
 
-cdef class KnmAutoConnectorWorkspace(ConnectorWorkspace):
-    def __init__(self, object owner, BaseSimulation sim, *args, **kwargs):
-        super().__init__(owner, sim, *args, **kwargs)
+cdef class KnmAutoConnectorWorkspace(KnmConnectorWorkspace):
+    def __init__(self, object owner, CarrierSignalMatrixSimulation sim, *args, **kwargs):
+        # Skip KnmConnectorWorkspace init call
+        ConnectorWorkspace.__init__(self, owner, sim, *args, **kwargs)
 
         # Here we automatically generate the coupling strings used
         # for generating the Knm matricies. We use the optical to optical
@@ -90,19 +92,25 @@ cdef class KnmAutoConnectorWorkspace(ConnectorWorkspace):
 
         # need these node ids for the simulation for indexing traces
         for i, p in enumerate(oports):
-            self.onode_ids[2*i] = sim.node_id(p.i)
-            self.onode_ids[2*i+1] = sim.node_id(p.o)
+            self.onode_ids[2*i] = sim.carrier.node_id(p.i)
+            self.onode_ids[2*i+1] = sim.carrier.node_id(p.o)
         
-        str_couplings = []
         for i, (conn, (f, t)) in enumerate(self.o2o.items()):
+            # TODO ddb should probably use some fixed index rather than a list of the order
+            # they are defined in the element definition
             a = oports.index(f.port)
             b = oports.index(t.port)
-            str_couplings.append(f"{a+1}{b+1}")
+            coupling = f"{a+1}{b+1}"
             self.oconn_info[i].from_port_idx = a
             self.oconn_info[i].to_port_idx = b
             self.oconn_info[i].K_ws_x = &self.Kws[2*i]
             self.oconn_info[i].K_ws_y = &self.Kws[2*i+1]
-    
+            knm = KnmMatrix(self.sim.model_data.homs_view, self.owner.name, coupling)
+            self.oconn_info[i].mtx = &knm.mtx
+            # Create the actual Knm matrix here based on the optical
+            # port coupling indices
+            setattr(self, f"K{coupling}", knm)
+
     def __dealloc__(self):
         if self.onode_ids:
             free(self.onode_ids)
@@ -222,17 +230,19 @@ cdef class KnmAutoConnectorWorkspace(ConnectorWorkspace):
     
     cdef void compute_scattering_matrices(KnmAutoConnectorWorkspace self):
         cdef:
-            NodeBeamParam *q_from
-            NodeBeamParam *q_to
             KnmInfo *info
-            complex_t qx_o_matched_trns, qy_o_matched_trns
-
+            complex_t[:,::1] view
+            
         for i in range(self.N_opt_conns):
             info = &self.oconn_info[i]
-            # Transmission
             if knm_ws_is_changing(info.K_ws_x) or knm_ws_is_changing(info.K_ws_y):
-                #compute_knm_matrix_bh(info.K_ws_x, info.K_ws_y, self.sim.homs_view, self.K12.data_view)
-                reverse_gouy_phases(self.K12.data_view, self.sim.homs_view, info.K_ws_x, info.K_ws_y, self.K12.data_view)
+                # Can't store memoryview in struct so have to do some converting here
+                view = <complex_t[:info.mtx.size1, :info.mtx.size2:1]>(info.mtx.ptr)
+                compute_knm_matrix_bh(info.K_ws_x, info.K_ws_y, self.sim.model_data.homs_view, view)
+                reverse_gouy_phases(view, self.sim.homs_view, info.K_ws_x, info.K_ws_y, view)
+
+                if self.sim.model_data.zero_K00:
+                    zero_tem00_phase(view, view)
 
-                #if self.sim.model_data.zero_K00:
-                #    zero_tem00_phase(self.K12.data_view, self.K12.data_view)
\ No newline at end of file
+                if not info.is_transmission: # if reflection...
+                    flip_odd_horizontal(view, self.sim.model_data.homs_view, view)
\ No newline at end of file