From e3077f6d2fc9c23b3a2bc46cbd3948b2cbd18193 Mon Sep 17 00:00:00 2001
From: wakonig_k <klaus.wakonig@psi.ch>
Date: Fri, 18 Jul 2025 11:33:13 +0200
Subject: [PATCH] feat(xbpms): add diag signal and normalize diff signals

---
 csaxs_bec/devices/epics/xbpms.py | 58 ++++++++++++++++++++++++--------
 1 file changed, 44 insertions(+), 14 deletions(-)

diff --git a/csaxs_bec/devices/epics/xbpms.py b/csaxs_bec/devices/epics/xbpms.py
index 27e5927..1c67e54 100644
--- a/csaxs_bec/devices/epics/xbpms.py
+++ b/csaxs_bec/devices/epics/xbpms.py
@@ -1,5 +1,6 @@
-from ophyd import Signal, Device, EpicsSignalRO
 from ophyd import Component as Cpt
+from ophyd import Device, EpicsSignalRO, Signal
+
 
 class SumSignal(Signal):
     def __init__(self, *args, **kwargs):
@@ -18,15 +19,23 @@ class SumSignal(Signal):
         return val1 + val2 + val3 + val4
 
     def describe(self):
+        source = [
+            self.parent.current1.pvname,
+            self.parent.current2.pvname,
+            self.parent.current3.pvname,
+            self.parent.current4.pvname,
+        ]
+        source = " / ".join(source)
         desc = {
             "shape": [],
             "dtype": "number",
-            "source": "PV: {} / {}".format(self.parent.current1.pvname, self.parent.current1.pvname),
+            "source": f"PV: {source}",
             "units": "",
             "precision": self.parent.current1.precision,
         }
         return desc
 
+
 class DiffXYSignal(Signal):
     def __init__(self, sum1, sum2, *args, **kwargs):
         self.sum1 = sum1
@@ -46,33 +55,54 @@ class DiffXYSignal(Signal):
         for signal in self.sum2:
             summed_2 += getattr(self.parent, signal).get()
 
-        return summed_1 - summed_2
+        _sum = summed_1 + summed_2
+        if _sum == 0:
+            return 0.0
+        return (summed_1 - summed_2) / _sum
 
     def describe(self):
+        source = [getattr(self.parent, signal).pvname for signal in self.sum1 + self.sum2]
+        source = " / ".join(source)
         desc = {
             "shape": [],
             "dtype": "number",
-            "source": "PV: {} / {}".format(self.parent.current1.pvname, self.parent.current1.pvname),
+            "source": f"PV: {source}",
             "units": "",
             "precision": self.parent.current1.precision,
         }
         return desc
 
+
 class BPMDevice(Device):
-    current1 = Cpt(EpicsSignalRO, ":Current1:MeanValue_RBV", kind="normal")
-    current2 = Cpt(EpicsSignalRO, ":Current2:MeanValue_RBV", kind="normal")
-    current3 = Cpt(EpicsSignalRO, ":Current3:MeanValue_RBV", kind="normal")
-    current4 = Cpt(EpicsSignalRO, ":Current4:MeanValue_RBV", kind="normal")
-    sum = Cpt(SumSignal, kind="hinted")
-    x = Cpt(DiffXYSignal, sum1=["current1", "current2"], sum2=["current3", "current4"])
-    y = Cpt(DiffXYSignal, sum1=["current1", "current3"], sum2=["current2", "current4"])
+    current1 = Cpt(EpicsSignalRO, ":Current1:MeanValue_RBV", kind="normal", doc="Current 1")
+    current2 = Cpt(EpicsSignalRO, ":Current2:MeanValue_RBV", kind="normal", doc="Current 2")
+    current3 = Cpt(EpicsSignalRO, ":Current3:MeanValue_RBV", kind="normal", doc="Current 3")
+    current4 = Cpt(EpicsSignalRO, ":Current4:MeanValue_RBV", kind="normal", doc="Current 4")
+    sum = Cpt(SumSignal, kind="hinted", doc="Sum of all currents")
+    x = Cpt(
+        DiffXYSignal,
+        sum1=["current1", "current2"],
+        sum2=["current3", "current4"],
+        doc="X difference signal",
+    )
+    y = Cpt(
+        DiffXYSignal,
+        sum1=["current1", "current3"],
+        sum2=["current2", "current4"],
+        doc="Y difference signal",
+    )
+    diag = Cpt(
+        DiffXYSignal,
+        sum1=["current1", "current4"],
+        sum2=["current2", "current3"],
+        doc="Diagonal difference signal",
+    )
 
     def __init__(self, prefix="", *args, **kwargs):
         super().__init__(*args, prefix=prefix, **kwargs)
-        
 
 
 if __name__ == "__main__":
-    dev = BPMDevice(name="bpm", prefix='X12SA-FE-XBPM1')
+    dev = BPMDevice(name="bpm", prefix="X12SA-FE-XBPM1")
     dev.wait_for_connection()
-    print(dev.read())
\ No newline at end of file
+    print(dev.read())