diff --git a/armsrc/appmain.c b/armsrc/appmain.c
index 0742625b7..10d57fbf5 100644
--- a/armsrc/appmain.c
+++ b/armsrc/appmain.c
@@ -1457,11 +1457,7 @@ static void UsbPacketReceived(bool cmd_ng, uint8_t *packet) {
             break;
         case CMD_PING:
             if (cmd_ng) {
-#ifdef WITH_FPC_HOST
-                cmd_send(CMD_ACK, reply_via_fpc, ((uint32_t *)data_ng)[0], ((uint32_t *)data_ng)[(datalen_ng - 1) / 4], 0, 0);
-#else
-                cmd_send(CMD_ACK, 0, ((uint32_t *)data_ng)[0], ((uint32_t *)data_ng)[(c->arg[0] - 1) / 4], 0, 0);
-#endif
+                reply_ng(CMD_PING, PM3_SUCCESS, data_ng, datalen_ng);
             } else {
 #ifdef WITH_FPC_HOST
                 cmd_send(CMD_ACK, reply_via_fpc, 0, 0, 0, 0);
@@ -1574,9 +1570,9 @@ void  __attribute__((noreturn)) AppMain(void) {
     usb_disable();
     usb_enable();
 
-    uint8_t rx[USB_PACKET_NG_MAXLEN];
+    uint8_t rx[USB_COMMANDNG_MAXLEN];
     UsbCommandNGPreamble *pre = (UsbCommandNGPreamble *)rx;
-    UsbCommandNGPostamble *post = (UsbCommandNGPostamble *)(rx + sizeof(UsbCommandNGPreamble) + USB_CMD_DATA_SIZE);
+    UsbCommandNGPostamble *post = (UsbCommandNGPostamble *)(rx + sizeof(UsbCommandNGPreamble) + USB_DATANG_SIZE);
 
     for (;;) {
         WDT_HIT();
@@ -1586,8 +1582,8 @@ void  __attribute__((noreturn)) AppMain(void) {
             bool error = false;
             size_t bytes = usb_read_ng(rx, sizeof(UsbCommandNGPreamble));
             if (bytes == sizeof(UsbCommandNGPreamble)) {
-                if (pre->magic == USB_PREAMBLE_MAGIC) { // New style NG command
-                    if (pre->length > USB_CMD_DATA_SIZE) {
+                if (pre->magic == USB_COMMANDNG_PREAMBLE_MAGIC) { // New style NG command
+                    if (pre->length > USB_DATANG_SIZE) {
                         Dbprintf("Packet frame with incompatible length: 0x%04x", pre->length);
                         error = true;
                     }
@@ -1599,7 +1595,7 @@ void  __attribute__((noreturn)) AppMain(void) {
                         }
                     }
                     if (!error) {                        // Get the postamble
-                        bytes = usb_read_ng(rx + sizeof(UsbCommandNGPreamble) + USB_CMD_DATA_SIZE, sizeof(UsbCommandNGPostamble));
+                        bytes = usb_read_ng(rx + sizeof(UsbCommandNGPreamble) + USB_DATANG_SIZE, sizeof(UsbCommandNGPostamble));
                         if (bytes != sizeof(UsbCommandNGPostamble)) {
                             Dbprintf("Packet frame error fetching postamble");
                             error = true;
diff --git a/client/cmdhw.c b/client/cmdhw.c
index 0442052e1..6bdd65585 100644
--- a/client/cmdhw.c
+++ b/client/cmdhw.c
@@ -440,17 +440,16 @@ static int CmdPing(const char *Cmd) {
 
 static int CmdPingNG(const char *Cmd) {
     uint32_t len = strtol(Cmd, NULL, 0);
-    if (len > USB_CMD_DATA_SIZE)
-        len = USB_CMD_DATA_SIZE;
+    if (len > USB_DATANG_SIZE)
+        len = USB_DATANG_SIZE;
     PrintAndLogEx(NORMAL, "Pinging with payload len=%d", len);
     clearCommandBuffer();
     UsbCommand resp;
-    uint8_t data[USB_CMD_DATA_SIZE] = {0};
+    uint8_t data[USB_DATANG_SIZE] = {0};
     uint16_t cmd = CMD_PING;
-    if (len >= 4)
-        ((uint32_t *)data)[0] = 0xAABBCCDD;
-    if (len >= 8)
-        ((uint32_t *)data)[(len - 1) / 4] = 0xDDCCBBAA;
+    if (len)
+    for (uint16_t i=0; i<len; i++)
+        data[i] = i & 0xFF;
     SendCommandNG(cmd, data, len);
     if (WaitForResponseTimeout(CMD_ACK, &resp, 1000)) {
         PrintAndLogEx(NORMAL, "PingNG successful");
diff --git a/client/comms.c b/client/comms.c
index ac323ec31..52fd80783 100644
--- a/client/comms.c
+++ b/client/comms.c
@@ -26,7 +26,7 @@ static pthread_t USB_communication_thread;
 
 // Transmit buffer.
 static UsbCommand txBuffer;
-static uint8_t txBufferNG[USB_PACKET_NG_MAXLEN];
+static uint8_t txBufferNG[USB_COMMANDNG_MAXLEN];
 size_t txBufferNGLen;
 static bool txBuffer_pending = false;
 static pthread_mutex_t txBufferMutex = PTHREAD_MUTEX_INITIALIZER;
@@ -97,7 +97,7 @@ void SendCommandNG(uint16_t cmd, uint8_t *data, size_t len) {
         PrintAndLogEx(NORMAL, "Sending bytes to proxmark failed - offline");
         return;
     }
-    if (len > USB_CMD_DATA_SIZE) {
+    if (len > USB_DATANG_SIZE) {
         PrintAndLogEx(WARNING, "Sending %d bytes of payload is too much, abort", len);
         return;
     }
@@ -115,7 +115,7 @@ void SendCommandNG(uint16_t cmd, uint8_t *data, size_t len) {
         pthread_cond_wait(&txBufferSig, &txBufferMutex);
     }
 
-    tx_pre->magic = USB_PREAMBLE_MAGIC;
+    tx_pre->magic = USB_COMMANDNG_PREAMBLE_MAGIC;
     tx_pre->length = len;
     tx_pre->cmd = cmd;
     memcpy(txBufferNG + sizeof(UsbCommandNGPreamble), data, len);
diff --git a/common/cmd.c b/common/cmd.c
index d560c60f7..42c72269b 100644
--- a/common/cmd.c
+++ b/common/cmd.c
@@ -30,6 +30,7 @@
  * @brief
  */
 #include "cmd.h"
+#include "crc16.h"
 
 #ifdef WITH_FPC_HOST
 // "Session" flag, to tell via which interface next msgs should be sent: USB or FPC USART
@@ -78,3 +79,53 @@ uint8_t cmd_send(uint64_t cmd, uint64_t arg0, uint64_t arg1, uint64_t arg2, void
 
     return sendlen;
 }
+
+uint8_t reply_ng(uint16_t cmd, int16_t status, uint8_t *data, size_t len) {
+    uint8_t txBufferNG[USB_REPLYNG_MAXLEN];
+    size_t txBufferNGLen;
+//    for (size_t i = 0; i < sizeof(txBufferNG); i++)
+//        ((uint8_t *)&txBufferNG)[i] = 0x00;
+
+    // Compose the outgoing command frame
+    UsbReplyNGPreamble *tx_pre = (UsbReplyNGPreamble *)txBufferNG;
+    tx_pre->magic = USB_REPLYNG_PREAMBLE_MAGIC;
+    tx_pre->cmd = cmd;
+    tx_pre->status = status;
+    if (len > USB_DATANG_SIZE) {
+        len = USB_DATANG_SIZE;
+        // overwrite status
+        tx_pre->status = PM3_EOVFLOW;
+    }
+    tx_pre->length = len;
+    uint8_t *tx_data = txBufferNG + sizeof(UsbReplyNGPreamble);
+    UsbReplyNGPostamble *tx_post = (UsbReplyNGPostamble *)(txBufferNG + sizeof(UsbReplyNGPreamble) + len);
+
+    // Add the (optional) content to the frame, with a maximum size of USB_DATANG_SIZE
+    if (data && len) {
+        for (size_t i = 0; i < len; i++) {
+            tx_data[i] = data[i];
+        }
+    }
+
+    uint8_t first, second;
+    compute_crc(CRC_14443_A, txBufferNG, sizeof(UsbReplyNGPreamble) + len, &first, &second);
+    tx_post->crc = (first << 8) + second;
+    txBufferNGLen = sizeof(UsbReplyNGPreamble) + len + sizeof(UsbReplyNGPostamble);
+
+
+    uint32_t sendlen = 0;
+    // Send frame and make sure all bytes are transmitted
+
+#ifdef WITH_FPC_HOST
+    if (reply_via_fpc) {
+        sendlen = usart_writebuffer(txBufferNG, txBufferNGLen);
+//        Dbprintf_usb("Sent %i bytes over usart", len);
+    } else {
+        sendlen = usb_write(txBufferNG, txBufferNGLen);
+    }
+#else
+    sendlen = usb_write(txBufferNG, txBufferNGLen);
+#endif
+
+    return sendlen;
+}
diff --git a/common/cmd.h b/common/cmd.h
index 858466dd3..a07ef35d0 100644
--- a/common/cmd.h
+++ b/common/cmd.h
@@ -40,6 +40,7 @@
 #include "proxmark3.h"
 
 uint8_t cmd_send(uint64_t cmd, uint64_t arg0, uint64_t arg1, uint64_t arg2, void *data, size_t len);
+uint8_t reply_ng(uint16_t cmd, int16_t status, uint8_t *data, size_t len);
 
 #endif // _PROXMARK_CMD_H_
 
diff --git a/include/usb_cmd.h b/include/usb_cmd.h
index 60077d630..0edf68dc8 100644
--- a/include/usb_cmd.h
+++ b/include/usb_cmd.h
@@ -25,6 +25,7 @@ typedef BYTE uint8_t;
 #endif
 
 #define USB_CMD_DATA_SIZE 512
+#define USB_DATANG_SIZE 512
 
 typedef struct {
     uint64_t cmd;
@@ -41,14 +42,30 @@ typedef struct {
     uint16_t cmd;
 } PACKED UsbCommandNGPreamble;
 
-#define USB_PREAMBLE_MAGIC 0x61334d50 // PM3a
+#define USB_COMMANDNG_PREAMBLE_MAGIC 0x61334d50 // PM3a
 
 typedef struct {
     uint16_t crc;
 } PACKED UsbCommandNGPostamble;
 
-#define USB_PACKET_NG_MINLEN (sizeof(UsbCommandNGPreamble) + sizeof(UsbCommandNGPostamble))
-#define USB_PACKET_NG_MAXLEN (sizeof(UsbCommandNGPreamble) + USB_CMD_DATA_SIZE + sizeof(UsbCommandNGPostamble))
+#define USB_COMMANDNG_MINLEN (sizeof(UsbCommandNGPreamble) + sizeof(UsbCommandNGPostamble))
+#define USB_COMMANDNG_MAXLEN (sizeof(UsbCommandNGPreamble) + USB_DATANG_SIZE + sizeof(UsbCommandNGPostamble))
+
+typedef struct {
+    uint32_t magic;
+    uint16_t length;  // length of the variable part, 0 if none.
+    uint16_t cmd;
+    int16_t  status;
+} PACKED UsbReplyNGPreamble;
+
+#define USB_REPLYNG_PREAMBLE_MAGIC 0x62334d50 // PM3b
+
+typedef struct {
+    uint16_t crc;
+} PACKED UsbReplyNGPostamble;
+
+#define USB_REPLYNG_MINLEN (sizeof(UsbReplyNGPreamble) + sizeof(UsbReplyNGPostamble))
+#define USB_REPLYNG_MAXLEN (sizeof(UsbReplyNGPreamble) + USB_DATANG_SIZE + sizeof(UsbReplyNGPostamble))
 
 #ifdef WITH_FPC_HOST
 // "Session" flag, to tell via which interface next msgs should be sent: USB or FPC USART
@@ -332,6 +349,31 @@ typedef struct {
 #define FLAG_NONEWLINE   0x0010
 #define FLAG_NOPROMPT    0x0100
 
+// Error codes
+
+// Success (no error)
+#define PM3_SUCCESS             0
+// Undefined error
+#define PM3_EUNDEF             -1
+// Invalid argument(s)
+#define PM3_EINVARG            -2
+// Operation not supported by device
+#define PM3_EDEVNOTSUPP        -3
+// Operation timed out
+#define PM3_ETIMEOUT           -4
+// Operation aborted (by user)
+#define PM3_EOPABORTED         -5
+// Not (yet) implemented
+#define PM3_ENOTIMPL           -6
+// Error while RF transmission
+#define PM3_ERFTRANS           -7
+// Input / output error
+#define PM3_EIO                -8
+// Buffer overflow
+#define PM3_EOVFLOW            -9
+// Software error
+#define PM3_ESOFT             -10
+
 
 // CMD_DEVICE_INFO response packet has flags in arg[0], flag definitions:
 /* Whether a bootloader that understands the common_area is present */