diff --git a/src/gateware/cxp.py b/src/gateware/cxp.py
index 280ca60..30dc17f 100644
--- a/src/gateware/cxp.py
+++ b/src/gateware/cxp.py
@@ -287,7 +287,7 @@ class CXP_Frame_Pipeline(Module, AutoCSR):
 
 class CXP_Grabber(Module, AutoCSR):
     # optimal stream packet size is 2 KiB - Section 9.5.2 (CXP-001-2021)
-    def __init__(self, host, roi_engine_count=8, res_width=16, count_width=31):
+    def __init__(self, host, roi_engine_count=1, res_width=16, count_width=31):
         assert count_width <= 31
 
         self.crc_error = CSR()
@@ -319,7 +319,7 @@ class CXP_Grabber(Module, AutoCSR):
         # select which roi engine can output rtio_input signal
         self.gate_data = rtlink.Interface(
             rtlink.OInterface(roi_engine_count),
-            # the 32th bits is for sentinel (gate detection)
+            # the extra MSB bits is for sentinel
             rtlink.IInterface(count_width+1, timestamped=False)
         )