diff --git a/DCCEXCommands.h b/DCCEXCommands.h
index 9e0dffd..8e34fea 100644
--- a/DCCEXCommands.h
+++ b/DCCEXCommands.h
@@ -137,7 +137,7 @@ ZZ(T,id,DCC,nn)          CHECK(DCCTurnout::create(id, (nn-1)/4+1, (nn-1)%4))
 ZZ(T,id,addr,subadd)     CHECK(DCCTurnout::create(id, addr, subadd)) 
 ZZ(T,id,pin,low,high)    CHECK(ServoTurnout::create(id, (VPIN)pin,low,high,1)) 
 ZZ(S,id,pin,pullup)      CHECK(Sensor::create(id,pin,pullup)) 
-ZZ(S,id)                 CHECK(Sensor::remove(p[0]))
+ZZ(S,id)                 CHECK(Sensor::remove(id))
 ZZ(S)                    for (auto *tt = Sensor::firstSensor; tt; tt = tt->nextSensor) {
                             REPLY("<Q %d %d %d>\n", tt->data.snum, tt->data.pin, tt->data.pullUp)
                          }           
@@ -238,7 +238,7 @@ ZZ(I,id,EXTT,vpin,home) // <I id EXTT vpin home> create an EXTT turntable
 
 
 ZZ(I,id,ADD,position,value,angle) // <I id ADD position value angle> add a position
-     auto tto = Turntable::get(p[0]);
+     auto tto = Turntable::get(id);
      // tto must exist, no more than 48 positions, angle 0 - 3600
      CHECK(tto && position <= 48 && angle >=0  && angle <= 3600)
      tto->addPosition(id,value,angle);
@@ -342,7 +342,7 @@ ZZ(D,ACK,RETRY,value)    DCCACK::setAckRetry(value);                   LCD(1, F(
 ZZ(C,WIFI,marker1,ssid,marker2,password)
  	// <C WIFI SSID PASSWORD>
     CHECK(marker1==0x7777 && marker2==0x7777)
-    WifiESP::setup((const char*)(com + p[2]), (const char*)(com + p[4]), WIFI_HOSTNAME, IP_PORT, WIFI_CHANNEL, WIFI_FORCE_AP);
+    WifiESP::setup((const char*)(com + ssid), (const char*)(com + password), WIFI_HOSTNAME, IP_PORT, WIFI_CHANNEL, WIFI_FORCE_AP);
 #endif
 
 ZZ(o,vpin)              IODevice::write(abs(vpin),vpin>0);
@@ -379,7 +379,7 @@ ZZ(a,linearaddress,activate)
     DCC::setAccessory((linearaddress - 1) / 4 + 1,(linearaddress - 1)  % 4 ,activate ^ accessoryCommandReverse);                                    
 ZZ(A,address,value)                 DCC::setExtendedAccessory(address,value);
 
-ZZ(w,cab,cv,value)   DCC::writeCVByteMain(p[0], p[1], p[2]);
+ZZ(w,cab,cv,value)   DCC::writeCVByteMain(cab,cv,value);
 ZZ(r,cab,cv) 
       CHECK(DCCWaveform::isRailcom())
       EXPECT_CALLBACK
diff --git a/DCCEXParser.cpp b/DCCEXParser.cpp
index d2f6ba3..de29106 100644
--- a/DCCEXParser.cpp
+++ b/DCCEXParser.cpp
@@ -328,12 +328,14 @@ void DCCEXParser::parseOne(Print *stream, byte *com, RingStream * ringStream)
         if (TrackManager::parseEqualSign(stream, params, p))
             return;
     
-
+    matchedCommandFormat = F("none");
+    checkFailedFormat = matchedCommandFormat;
     if (execute(com,stream, opcode, params, p, ringStream)) return;
 
-    // TODO magnificent diagnostics 
-    StringFormatter::send(stream, F("<X>\n"), opcode);
-    if (opcode >= ' ' && opcode <= '~') {
+    // TODO magnificent diagnostics
+    StringFormatter::send(stream, F("<X>\n"));
+     DIAG(F("Command format <%<>  failed CHECK(%S)\n"), matchedCommandFormat, checkFailedFormat);
+     if (opcode >= ' ' && opcode <= '~') {
         DIAG(F("Opcode=%c params=%d"), opcode, params);
         for (int i = 0; i < params; i++)
             DIAG(F("p[%d]=%d (0x%x)"), i, p[i], p[i]);
@@ -373,11 +375,9 @@ bool DCCEXParser::funcmap(int16_t cab, byte value, byte fstart, byte fstop)
   return true;
 }
 
-#ifdef DCC_ACCESSORY_COMMAND_REVERSE
- const bool accessoryCommandReverse = true;
-#else    
- const bool accessoryCommandReverse = false;
-#endif
+const FSH* DCCEXParser::matchedCommandFormat=nullptr;
+const FSH* DCCEXParser::checkFailedFormat=nullptr; 
+
 
 // Having broken the command into opcode and parameters, we now execute the command
 // The actual commands and their parameter mappings are in DCCEXCommands.h
diff --git a/DCCEXParser.h b/DCCEXParser.h
index ff06fb7..fbeb544 100644
--- a/DCCEXParser.h
+++ b/DCCEXParser.h
@@ -42,7 +42,13 @@ struct DCCEXParser
    static const int MAX_COMMAND_PARAMS=10;  // Must not exceed this
  
    private:
-  
+   static const FSH * matchedCommandFormat;
+   static const FSH * checkFailedFormat;
+   #ifdef DCC_ACCESSORY_COMMAND_REVERSE
+   static const bool accessoryCommandReverse = true;
+  #else    
+   static const bool accessoryCommandReverse = false;
+  #endif
     static const int16_t MAX_BUFFER=50;  // longest command sent in
     static int16_t splitValues( int16_t result[MAX_COMMAND_PARAMS], byte * command, bool usehex);
     static bool execute(byte * command, Print * stream, byte opcode, byte params, int16_t p[], RingStream * ringStream);
diff --git a/DCCEXParserMacros.h b/DCCEXParserMacros.h
index ed27bb3..78d7035 100644
--- a/DCCEXParserMacros.h
+++ b/DCCEXParserMacros.h
@@ -24,11 +24,11 @@
 #define Z8(op,_1,_2,_3,_4,_5,_6,_7) ZPREP(op,7) ZZZ(0,_1) ZZZ(1,_2) ZZZ(2,_3) ZZZ(3,_4) ZZZ(4,_5) ZZZ(5,_6) ZZZ(6,_7)
 
 #define ZRIP(count) CONCAT(Z,count)
-#define ZZ(...) ZRIP(FOR_EACH_NARG(__VA_ARGS__))(__VA_ARGS__)
+#define ZZ(...) ZRIP(FOR_EACH_NARG(__VA_ARGS__))(__VA_ARGS__) matchedCommandFormat = F( #__VA_ARGS__);
  
 #define ZZBEGIN if (false) {
 #define ZZEND return true; } return false;
-#define CHECK(x) if (!(x)) return false;
+#define CHECK(x) if (!(x)) { checkFailedFormat=F(#x); return false;}
 #define REPLY(format,...) StringFormatter::send(stream,F(format), ##__VA_ARGS__);
 #define EXPECT_CALLBACK CHECK(stashCallback(stream, p, ringStream))
 
diff --git a/StringFormatter.cpp b/StringFormatter.cpp
index 35a4901..daac88c 100644
--- a/StringFormatter.cpp
+++ b/StringFormatter.cpp
@@ -123,6 +123,7 @@ void StringFormatter::send2(Print * stream,const FSH* format, va_list args) {
       case 's': stream->print(va_arg(args, char*)); break;
       case 'e': printEscapes(stream,va_arg(args, char*)); break;
       case 'E': printEscapes(stream,(const FSH*)va_arg(args, char*)); break;
+      case '<': printCmdFormat(stream,(const FSH*)va_arg(args, char*)); break;
       case 'S':
       { 
         const FSH*  flash= (const FSH*)va_arg(args, char*);
@@ -202,15 +203,27 @@ void StringFormatter::printEscapes(Print * stream,char * input) {
 
 void StringFormatter::printEscapes(Print * stream, const FSH * input) {
  
- if (!stream) return;
- char* flash=(char*)input;
- for(int i=0; ; ++i) {
-  char c=GETFLASH(flash+i);
-  printEscape(stream,c);
-  if (c=='\0') return;
+  if (!stream) return;
+  char* flash=(char*)input;
+  for(int i=0; ; ++i) {
+   char c=GETFLASH(flash+i);
+   printEscape(stream,c);
+   if (c=='\0') return;
+  }
  }
-}
 
+ void StringFormatter::printCmdFormat(Print * stream, const FSH * input) {
+ 
+  if (!stream) return;
+  char* flash=(char*)input;
+  for(int i=0; ; ++i) {
+   char c=GETFLASH(flash+i);
+   if (c=='\0') return;
+   if (c==',') c=' ';
+   stream->write(c);
+  }
+ }
+  
 void StringFormatter::printEscape( char c) {
   printEscape(&USB_SERIAL,c);
 }
diff --git a/StringFormatter.h b/StringFormatter.h
index c046ec7..c3a5859 100644
--- a/StringFormatter.h
+++ b/StringFormatter.h
@@ -43,6 +43,7 @@ class StringFormatter
     
     static void printEscapes(Print * serial,char * input);
     static void printEscapes(Print * serial,const FSH* input);
+    static void printCmdFormat(Print * serial,const FSH* input);
     static void printEscape(Print * serial, char c);
 
     // DIAG support