diff --git a/sis8300bcmApp/Db/sis8300bcm-acct.template b/sis8300bcmApp/Db/sis8300bcm-acct.template
index acf5e6d77f03bcddfe29304b7b533e1fbf991ffc..6139f7f0751b8505622b9498c9fddccbf580e93c 100644
--- a/sis8300bcmApp/Db/sis8300bcm-acct.template
+++ b/sis8300bcmApp/Db/sis8300bcm-acct.template
@@ -1364,4 +1364,21 @@ record(ao, "$(P)$(R)LIThreshold")
     info(autosaveFields, "VAL")
 }
 
+record(bo, "$(P)$(R)BeamAbsenceMask")
+{
+    field(DTYP, "asynInt32")
+    field(OUT,  "@asyn($(PORT),$(ADDR=0),$(TIMEOUT=1))BCM.ACCT.BEAM_ABSENCE")
+    field(ZNAM, "Disable")
+    field(ONAM, "Enable")
+    field(ASG,  "critical")
+    info(autosaveFields, "VAL")
+}
+record(bi, "$(P)$(R)BeamAbsenceMaskR")
+{
+    field(DTYP, "asynInt32")
+    field(INP,  "@asyn($(PORT),$(ADDR=0),$(TIMEOUT=1))BCM.ACCT.BEAM_ABSENCE")
+    field(SCAN, "I/O Intr")
+    field(ZNAM, "Disabled")
+    field(ONAM, "Enabled")
+}
 
diff --git a/sis8300bcmApp/src/sis8300bcm.cpp b/sis8300bcmApp/src/sis8300bcm.cpp
index fce8414c087b01fbcb96ec0b84210c8ce3ea6e51..6d8715af07fd94b262b77e10cf500b1b01baead4 100644
--- a/sis8300bcmApp/src/sis8300bcm.cpp
+++ b/sis8300bcmApp/src/sis8300bcm.cpp
@@ -277,6 +277,7 @@ sis8300bcm::sis8300bcm(const char *portName, const char *devicePath,
     createParam(BCMAcctAutoFlatTopStartString,              asynParamFloat64,   &BCMAcctAutoFlatTopStart);
     createParam(BCMAcctAutoFlatTopEndString,                asynParamFloat64,   &BCMAcctAutoFlatTopEnd);
     createParam(BCMAcctAutoFlatTopEnableString,             asynParamInt32,     &BCMAcctAutoFlatTopEnable);
+    createParam(BCMAcctBeamAbsenceString,                   asynParamInt32,     &BCMAcctBeamAbsence);
     // DIFF block, channel specific
     createParam(BCMDiffSourceAString,                       asynParamInt32,     &BCMDiffSourceA);
     createParam(BCMDiffSourceBString,                       asynParamInt32,     &BCMDiffSourceB);
@@ -1397,6 +1398,13 @@ int sis8300bcm::deviceDone()
             return ret;
         }
         setIntegerParam(addr, BCMAcctMaxPulseLength, uintValue);
+
+        ret = sis8300drvbcm_get_channel_beam_absence(mDeviceHandle, addr, &uintValue);
+        if (ret) {
+            asynPrintError(pasynUserSelf, "sis8300drvbcm_get_channel_beam_absence returned %d", ret);
+            return ret;
+        }
+        setIntegerParam(addr, BCMAcctBeamAbsence, uintValue);
     }
 
     // readout DIFF parameters
@@ -1998,6 +2006,11 @@ asynStatus sis8300bcm::writeInt32(asynUser *pasynUser, epicsInt32 value)
         if (ret) {
             asynPrintError(pasynUser, "sis8300drvbcm_set_channel_auto_flattop_enable returned %d", ret);
         }
+    } else if (function == BCMAcctBeamAbsence) {
+        ret = sis8300drvbcm_set_channel_beam_absence(mDeviceHandle, addr, value);
+        if (ret) {
+            asynPrintError(pasynUser, "sis8300drvbcm_set_channel_beam_absence returned %d", ret);
+        }
     } else if (function == BCMFiberOutDataSelect) {
         ret = sis8300drvbcm_set_fiber_out_data_select(mDeviceHandle, addr, value);
         if (ret) {
diff --git a/sis8300bcmApp/src/sis8300bcm.h b/sis8300bcmApp/src/sis8300bcm.h
index a4e9df63052efbffa4ad7d3435b9d01a6ca5a1a8..adc4a9b26a947e99a224a29352b65b9b634ebb92 100644
--- a/sis8300bcmApp/src/sis8300bcm.h
+++ b/sis8300bcmApp/src/sis8300bcm.h
@@ -173,6 +173,7 @@
 #define BCMAcctAutoFlatTopStartString                "BCM.ACCT.AUTO_FLATTOP_START"
 #define BCMAcctAutoFlatTopEndString                  "BCM.ACCT.AUTO_FLATTOP_END"
 #define BCMAcctAutoFlatTopEnableString               "BCM.ACCT.AUTO_FLATTOP_ENABLE"
+#define BCMAcctBeamAbsenceString                     "BCM.ACCT.BEAM_ABSENCE"
 // DIFF block, channel specific
 #define BCMDiffSourceAString                         "BCM.DIFF.SOURCE_A"
 #define BCMDiffSourceBString                         "BCM.DIFF.SOURCE_B"
@@ -400,6 +401,7 @@ protected:
     int BCMAcctAutoFlatTopStart;
     int BCMAcctAutoFlatTopEnd;
     int BCMAcctAutoFlatTopEnable;
+    int BCMAcctBeamAbsence;
     // DIFF block, channel specific
     int BCMDiffSourceA;
     int BCMDiffSourceB;
diff --git a/vendor/ess/lib/sis8300bcm_reg.h b/vendor/ess/lib/sis8300bcm_reg.h
index b3073721fb6f19c2b5caaf018535b6b4e7505bc7..4b9ca9bc608b60e3f4570beb2850ded009168bb4 100644
--- a/vendor/ess/lib/sis8300bcm_reg.h
+++ b/vendor/ess/lib/sis8300bcm_reg.h
@@ -154,6 +154,7 @@ extern "C" {
 #define SIS8300BCM_ACCT_X_AUTO_FLATTOP_RISING_OFF       0x036
 #define SIS8300BCM_ACCT_X_AUTO_FLATTOP_FALLING_OFF      0x037
 #define SIS8300BCM_ACCT_X_AUTO_FLATTOP_ENABLE_OFF       0x038
+#define SIS8300BCM_ACCT_X_BEAM_ABSENCE_OFF              0x039
 
 /*
  DIFF block registers
diff --git a/vendor/ess/lib/sis8300drvbcm.c b/vendor/ess/lib/sis8300drvbcm.c
index 7e51093e88c6044b1157e5e1c9c7fb83edb3ef7c..718a06fec94c3c026454c28f2c0730bbb174779c 100644
--- a/vendor/ess/lib/sis8300drvbcm.c
+++ b/vendor/ess/lib/sis8300drvbcm.c
@@ -2979,6 +2979,26 @@ int sis8300drvbcm_get_channel_auto_flattop_enable(sis8300drv_usr *sisuser, unsig
     return ret;
 }
 
+// used to control beam absence enable
+int sis8300drvbcm_set_channel_beam_absence(sis8300drv_usr *sisuser, unsigned int channel, unsigned int enable)
+{
+    unsigned int reg = SIS8300BCM_CHANNEL_BLOCK_BASE + \
+            (SIS8300BCM_CHANNEL_BLOCK_SIZE * channel) + \
+            SIS8300BCM_ACCT_BANK_OFF + \
+            SIS8300BCM_ACCT_X_BEAM_ABSENCE_OFF;
+    int ret = sis8300drv_reg_write(sisuser, reg, enable);
+    return ret;
+}
+int sis8300drvbcm_get_channel_beam_absence(sis8300drv_usr *sisuser, unsigned int channel, unsigned int *enable)
+{
+    unsigned int reg = SIS8300BCM_CHANNEL_BLOCK_BASE + \
+            (SIS8300BCM_CHANNEL_BLOCK_SIZE * channel) + \
+            SIS8300BCM_ACCT_BANK_OFF + \
+            SIS8300BCM_ACCT_X_BEAM_ABSENCE_OFF;
+    int ret = sis8300drv_reg_read(sisuser, reg, enable);
+    return ret;
+}
+
 // used to control fiber out data select
 int sis8300drvbcm_set_fiber_out_data_select(sis8300drv_usr *sisuser, unsigned int channel, unsigned int selection)
 {
diff --git a/vendor/ess/lib/sis8300drvbcm.h b/vendor/ess/lib/sis8300drvbcm.h
index 93b3c59fb2aa5ba3ca2c5f0c7834ed1c21c31428..278c32435b7841019b6ffb34247b8cbd7a13abd0 100644
--- a/vendor/ess/lib/sis8300drvbcm.h
+++ b/vendor/ess/lib/sis8300drvbcm.h
@@ -226,6 +226,8 @@ int sis8300drvbcm_set_channel_auto_flattop_end(sis8300drv_usr *sisuser, unsigned
 int sis8300drvbcm_get_channel_auto_flattop_end(sis8300drv_usr *sisuser, unsigned int channel, double *end);
 int sis8300drvbcm_set_channel_auto_flattop_enable(sis8300drv_usr *sisuser, unsigned int channel, unsigned int enable);
 int sis8300drvbcm_get_channel_auto_flattop_enable(sis8300drv_usr *sisuser, unsigned int channel, unsigned int *enable);
+int sis8300drvbcm_set_channel_beam_absence(sis8300drv_usr *sisuser, unsigned int channel, unsigned int enable);
+int sis8300drvbcm_get_channel_beam_absence(sis8300drv_usr *sisuser, unsigned int channel, unsigned int *enable);
 int sis8300drvbcm_set_channel_leaky_coefficient(sis8300drv_usr *sisuser, unsigned int channel, double coefficient);
 int sis8300drvbcm_get_channel_leaky_coefficient(sis8300drv_usr *sisuser, unsigned int channel, double *coefficient);
 int sis8300drvbcm_set_channel_leaky_threshold(sis8300drv_usr *sisuser, unsigned int channel, double threshold);