diff --git a/site_ansto/instrument/bilby/config/chopper/chopper.tcl b/site_ansto/instrument/bilby/config/chopper/chopper.tcl
index 87d02deb..462756e2 100644
--- a/site_ansto/instrument/bilby/config/chopper/chopper.tcl
+++ b/site_ansto/instrument/bilby/config/chopper/chopper.tcl
@@ -4,14 +4,14 @@ namespace eval chopper {
   set t0_chopper_id_simvar 1
 }
 
-if {$sim_mode == false} {
+if {$::chopper::sim_mode == false} {
   MakeAsyncProtocol std
+  std sendterminator "0x0D0x0A0"
+  std replyterminator "0x0D0x0A00x20"
   MakeAsyncQueue chopsel std chopsel1-bilby 30000
 }
 ::utility::macro::getset int t0_chopper_id {args} {
-  variable sim_mode [SplitReply [chopper_simulation]]
-
-  if {$sim_mode == false} {
+  if {$::chopper::sim_mode == false} {
     if {$args == ""} {
       chopsel send {get master chopper}
       return "t0_chopper_id = [SplitReply [chopsel send {get master chopper}]]"