diff --git a/iocBoot/iocvxWorks/st_SIS3820.iocsh b/iocBoot/iocvxWorks/st_SIS3820.iocsh
index 8a3cd046b5a530d71c795ae21d6d1f3e78676a66..7db60428ccd7b4700760b504fb861bf511863ff4 100644
--- a/iocBoot/iocvxWorks/st_SIS3820.iocsh
+++ b/iocBoot/iocvxWorks/st_SIS3820.iocsh
@@ -16,7 +16,7 @@ epicsEnvSet("MODEL",                    "SIS3820")
 #                  signals,
 #                  use DMA
 #                  fifoBufferWords)
-drvSIS3820Config($(PORT), 0xA8000000, 224, 6, $(MAX_CHANS), $(MAX_SIGNALS), 1, 0x2000)
+drvSIS3820Config($(PORT), 0xA8000000, 224, 6, $(MAX_CHANS), $(MAX_SIGNALS), 1, 0x20000)
 
 # This loads the scaler record and supporting records
 dbLoadRecords("$(STD)/stdApp/Db/scaler32.db", "P=$(PREFIX), S=scaler1, DTYP=Asyn Scaler, OUT=@asyn($(PORT)), FREQ=50000000")