diff --git a/site_ansto/instrument/config/environment/hiden_xcs.sct b/site_ansto/instrument/config/environment/hiden_xcs.sct
index 251400fc..4d43597a 100644
--- a/site_ansto/instrument/config/environment/hiden_xcs.sct
+++ b/site_ansto/instrument/config/environment/hiden_xcs.sct
@@ -188,10 +188,14 @@ driver hiden_xcs = {
 @  }
 @  if { [hpropexists [sct] target] } {
 @    set pid [pid_humidity ${tc_root} [sct target] ${data}]
+}
+  code pid_function pid_humidity = {
 @    set path [pathname [sct]]
+@    set sign 1
 @    foreach node [list analog/sp1 analog/sp2] {
-@      set pid [expr -${pid}]
-@      hsetprop ${path}/${node} bias_humidity ${pid}
+@      set sign [expr -${sign}]
+@      set signed_pid [expr ${sign} * ${pid}]
+@      hsetprop ${path}/${node} bias_humidity ${signed_pid}
 @      if { [hpropexists ${path}/${node} target] } {
 @        hset ${path}/${node} [hgetpropval ${path}/${node} target]
 @      } else {
@@ -214,6 +218,11 @@ driver hiden_xcs = {
 @  sct targets ${targets}
 @  if { [hpropexists [sct] target] } {
 @    set pid [pid_flow ${tc_root} [sct target] ${data}]
+@# cut this function short
+@  return ${nextState}
+}
+  code pid_function pid_flow = {
+@  set path [pathname [sct]]
 @    foreach node [list analog/sp1 analog/sp2] {
 @      hsetprop ${path}/${node} bias_flow ${pid}
 @      if { [hpropexists ${path}/${node} target] } {
@@ -223,7 +232,6 @@ driver hiden_xcs = {
 @      }
 @    }
 @  }
-@  return ${nextState}
   }
   code write_function write_digital = {
    }