diff --git a/site_ansto/instrument/config/environment/temperature/oxford_mercury.sct b/site_ansto/instrument/config/environment/temperature/oxford_mercury.sct
index 5fed0357..12d9d3a3 100644
--- a/site_ansto/instrument/config/environment/temperature/oxford_mercury.sct
+++ b/site_ansto/instrument/config/environment/temperature/oxford_mercury.sct
@@ -63,7 +63,7 @@ for i in range(8):
     var nick = { type=text; readable = 15; read_command = 'READ:DEV:DB5.P1:PRES:NICK'; read_function = rdText; }
     var valve = {
       conditional = '[string equal -nocase [string index ${cards} 3] V] && [string equal -nocase [string index ${assoc} 4] 4]';
-      read_command = 'READ:DEV:DB4.G1:AUX:SIG:OPEN';
+      read_command = 'READ:DEV:DB4.G1:AUX:SIG:PERC';
     }
     var setpoint = {
       conditional = '[string equal -nocase [string index ${cards} 3] V] && [string equal -nocase [string index ${assoc} 4] 4]';
@@ -80,7 +80,7 @@ for i in range(8):
     var nick = { type=text; readable = 15; read_command = 'READ:DEV:DB8.P1:PRES:NICK'; read_function = rdText; }
     var valve = {
       conditional = '[string equal -nocase [string index ${cards} 3] V] && [string equal -nocase [string index ${assoc} 7] 4]';
-      read_command = 'READ:DEV:DB4.G1:AUX:SIG:OPEN';
+      read_command = 'READ:DEV:DB4.G1:AUX:SIG:PERC';
     }
     var setpoint = {
       conditional = '[string equal -nocase [string index ${cards} 3] V] && [string equal -nocase [string index ${assoc} 7] 4]';
@@ -95,7 +95,7 @@ for i in range(8):
     conditional = '[string equal -nocase [string index ${cards} 3] V]';
     priv = user; type = float;
     var sensor = {
-      readable = 5; read_command = 'READ:DEV:DB4.G1:AUX:SIG:OPEN';
+      readable = 5; read_command = 'READ:DEV:DB4.G1:AUX:SIG:PERC';
     }
     var nick = { type=text; readable = 15; read_command = 'READ:DEV:DB4.G1:AUX:NICK'; read_function = rdText; }
     var setpoint = {
@@ -116,18 +116,17 @@ for i in range(8):
   code read_function rdValue = {
     @TCL
     set value [lindex [split "${data}" ":"] end]
-    if {[string equal -nocase [string index ${value} end] K]} {
-      set value [string range ${value} 0 end-1]
-    }
-    if {[string equal -nocase ${value} NaN]} {
+    if {[string equal -nocase -length 3 ${value} NaN]} {
       set value 0
     }
-    if {[string equal -nocase ${value} inf] || [string equal -nocase ${value} -inf]} {
+    if {[string equal -nocase -length 3 ${value} inf] || [string equal -nocase -length 4 ${value} -inf]} {
       set value 0
     }
-    if {![string is double ${value}]} {
+    if {![string is digit [string index ${value} 0]]} {
       set value 0
     }
+    debug_log ${tc_root} 1 "rdValue tc_root=${tc_root} sct=[sct] result=[sct result]"
+    debug_log ${tc_root} 1 "rdValue tc_root=${tc_root} data=${data} value=${value}"
     scan ${value} "%g" data
     @END
   }