From 9ca5af45077224cbd2a6457059f105e8cd758ee1 Mon Sep 17 00:00:00 2001
From: smathis <stefan.mathis@psi.ch>
Date: Fri, 20 Sep 2024 13:13:13 +0200
Subject: [PATCH] In the poll method, it is now checked whether the parameter
 library has been initialized. If this isn't the case, the poll is repeated
 (this is triggered by returning an error from the poll method)

---
 sinqEPICSApp/src/C804Axis.cpp | 38 +++++++++++++++++++++++++++--------
 1 file changed, 30 insertions(+), 8 deletions(-)

diff --git a/sinqEPICSApp/src/C804Axis.cpp b/sinqEPICSApp/src/C804Axis.cpp
index c1e1500..b0905db 100644
--- a/sinqEPICSApp/src/C804Axis.cpp
+++ b/sinqEPICSApp/src/C804Axis.cpp
@@ -55,7 +55,7 @@ asynStatus C804Axis::poll(bool *moving)
     // function should be called at the end of a poll implementation.
     asynStatus status_callback = callParamCallbacks();
     if (status_callback != asynSuccess)
-    {d
+    {
         asynPrint(pC_->pasynUserSelf, ASYN_TRACE_ERROR,
                   "%s: Updating the parameter library failed for axis %d\n", functionName, axisNo_);
         return status_callback;
@@ -131,20 +131,42 @@ asynStatus C804Axis::poll_no_param_lib_update(bool *moving)
     save the read result to the member variable earlier), since the parameter library
     is updated at a later stage!
     */
-    pC_->getDoubleParam(axisNo_, pC_->motorRecResolution_, &motorRecResolution_);
+    status = pC_->getDoubleParam(axisNo_, pC_->motorRecResolution_, &motorRecResolution_);
+
 
-	asynPrint(pC_->pasynUserSelf,ASYN_TRACE_FLOW,"Poll axis %d\n", axisNo_);
 
     /*
-    We know that the motor resolution must not be zero. During the startup of the
-    IOC, polls can happen before the record is fully initialized. In that case,
-    all values are zero.
-    */
-    if (motorRecResolution_ == 0)
+    The poll function might be called at IOC startup before the parameter 
+    library has been fully initialized. In this case, calling getDoubleParam 
+    returns the error status 10 (asynParamUndefined). Returning an asynError
+    from the poll method means that the poll is repeated. This is exactly what
+    we want, because this means that the poll will be repeated until the
+    parameter library has been initialized.
+    
+    asynStatus is defined as 
+
+    typedef enum {
+        asynSuccess,asynTimeout,asynOverflow,asynError,asynDisconnected,asynDisabled
+    }asynStatus;
+
+    in asynDriver.h (see https://github.com/epics-modules/asyn/blob/master/asyn/asynDriver/asynDriver.h),
+    Therefore, it should only have the values 0 to 5. However, the enum value 
+    range is extended in paramErrors.h (https://github.com/epics-modules/asyn/blob/master/asyn/asynPortDriver/paramErrors.h)
+     */
+    if (status == asynParamUndefined) 
     {
+        asynPrint(pC_->pasynUserSelf, ASYN_TRACE_FLOW,
+                  "%s: Parameter library is not yet initialized. Repeating poll on axis %d\n", functionName, axisNo_);
+        return asynError;
+    } 
+    else if (status != asynSuccess) 
+    {
+        asynPrint(pC_->pasynUserSelf, ASYN_TRACE_ERROR,
+                  "%s: Reading the motor resolution failed for axis %d\n (asynStatus = %d)", functionName, axisNo_, status);
         return asynError;
     }
 
+
     /*
     Assume that the axis does not have a status problem. If it does have a
     problem, this value will be overwritten further below. Setting this value