diff --git a/camlibs/sierra/sierra-usbwrap.c b/camlibs/sierra/sierra-usbwrap.c
index 5b0affc8b..87526cf4a 100644
--- a/camlibs/sierra/sierra-usbwrap.c
+++ b/camlibs/sierra/sierra-usbwrap.c
@@ -1,6 +1,7 @@
 /* sierra_usbwrap.c
  *
- * Copyright © 2002 Lutz Müller <lutz@users.sourceforge.net>
+ * Copyright 2002 Lutz Müller <lutz@users.sourceforge.net>
+ * Copyright 2012-2013 Marcus Meissner <marcus@jet.franken.de>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -123,7 +124,37 @@ cmdbyte (unsigned int type, unsigned char nr) {
 #define UW_PACKET_DATA ((uw4c_t){ 0x02, 0x00, 0xff, 0x9f })
 #define UW_PACKET_STAT ((uw4c_t){ 0x03, 0x00, 0xff, 0x9f })
 
+#define UW_MAGIC_OUT ((uw4c_t){ 'U','S','B','C' })
+#define UW_MAGIC_IN  ((uw4c_t){ 'U','S','B','S' })
+
 #pragma pack(1)
+/* This is linux/include/linux/usb/storage.h, struct bulk_cb_wrap
+ * 31 byte length */
+typedef struct
+{
+      uw4c_t magic;             /* The letters U S B C for packets sent to camera */
+      uw32_t tag;               /* The SCSI command tag */
+      uw32_t rw_length;         /* Length of data to be read or written next */
+      unsigned char flags;      /* in / out flag mostly */
+      unsigned char lun;        /* 0 here */
+      unsigned char length;     /* of the CDB... but 0x0c is used here in the traces */
+      unsigned char cdb[16];    
+} uw_header_t;
+
+/*
+ * This is the end response block from the camera looks like this:
+ *
+ * This is the generic bulk style USB Storage response block.
+ *
+ * linux/include/linux/usb/storage.h, struct bulk_cs_wrap */
+typedef struct
+{
+      uw4c_t magic;     /* The letters U S B S for packets from camera */
+      uw32_t tag;       /* A copy of whatever value the host made up */
+      uw32_t residue;   /* residual read? */
+      char   status;    /* status byte */
+} uw_response_t;
+
 /*
  * Data packet sent along with a UW_REQUEST_RDY:
  */
@@ -165,16 +196,6 @@ typedef struct
       uw32_t size;             /* The size of data waiting to be sent by camera */
 } uw_size_t;
 
-/*
- * The end of the response from the camera looks like this:
- */
-typedef struct
-{
-      uw4c_t magic;    /* The letters U S B S for packets from camera */
-      uw32_t sessionid;        /* A copy of whatever value the host made up */
-      char   zero[5];  /* 00 00 00 00 00 */
-} uw_response_t;
-
 typedef struct
 {
       unsigned char cmd;
@@ -184,6 +205,99 @@ typedef struct
 } uw_scsicmd_t;
 #pragma pack()
 
+static int ums_tag = 0x42424242;
+
+static int
+scsi_wrap_cmd(
+	GPPort *dev, int todev,
+	char *cmd, unsigned int cmdlen,
+	char *sense, unsigned int senselen,
+	char *data, unsigned int size
+) {
+	GPPortInfo	info;
+	GPPortType	type;
+	uw_header_t	hdr;
+	uw_response_t	rsp;
+	int		ret;
+
+	ret = gp_port_get_info (dev, &info);
+	if (ret != GP_OK) return ret;
+
+	ret = gp_port_info_get_type (info, &type);
+	if (ret != GP_OK) return ret;
+
+	if (type == GP_PORT_USB_SCSI)
+		/* just send it to the generic SCSI stack */
+		return gp_port_send_scsi_cmd (
+			dev, todev,
+			cmd, cmdlen,
+			sense, senselen,
+			data, size
+		);
+
+	/* Assuming plain USB, emulating SCSI ... */
+
+	memset(&hdr, 0, sizeof(hdr));
+	hdr.magic	= UW_MAGIC_OUT;
+	hdr.tag		= uw_value(ums_tag);
+	ums_tag++;
+	hdr.rw_length	= uw_value(size);
+	hdr.length	= 12; /* seems to be always 12, even as we send 16 byte CDBs */
+	hdr.flags	= todev?0:(1<<7);
+	hdr.lun		= 0;
+
+	memcpy(hdr.cdb, cmd, cmdlen);
+
+	/* WRITE scsi header / cdb */
+	if ((ret=gp_port_write(dev, (char*)&hdr, sizeof(hdr))) < GP_OK) {
+		GP_DEBUG( "scsi_wrap_cmd *** FAILED to write scsi cmd" );
+		return GP_ERROR_IO;
+	}
+	/* WRITE / READ data blob */
+	if (todev) {
+		if ((ret=gp_port_write(dev, (char*)data, size)) < GP_OK) {
+			GP_DEBUG( "scsi_wrap_cmd *** FAILED to write scsi data" );
+			return GP_ERROR_IO;
+		}
+	} else {
+		if ((ret=gp_port_read(dev, (char*)data, size)) < GP_OK) {
+			GP_DEBUG( "scsi_wrap_cmd *** FAILED to read scsi data" );
+			return GP_ERROR_IO;
+		}
+	}
+
+	/* READ RESPONSE */
+	memset(&rsp, 0, sizeof(rsp));
+
+	GP_DEBUG( "usb_wrap_OK" );
+	if ((ret = gp_port_read(dev, (char*)&rsp, sizeof(rsp))) != sizeof(rsp)) {
+		gp_log (GP_LOG_DEBUG, GP_MODULE, "scsi_wrap_cmd *** FAILED (%d vs %d bytes)", (int)sizeof(rsp), ret );
+		if (ret < GP_OK)
+			return ret;
+		return GP_ERROR;
+	}
+	if (	!UW_EQUAL(rsp.magic, UW_MAGIC_IN) ||
+		!UW_EQUAL(rsp.tag, hdr.tag))
+	{
+		GP_DEBUG( "scsi_wrap_cmd wrong session *** FAILED" );
+		return GP_ERROR;
+	}
+	/*
+	 * 32bit residual length (0) and 8 bit status (0) are good.
+	 */
+	if (	rsp.residue.c1 != 0 ||
+		rsp.residue.c2 != 0 ||
+		rsp.residue.c3 != 0 ||
+		rsp.residue.c4 != 0 ||
+		rsp.status != 0) {
+		GP_DEBUG( "Error: scsi_wrap_cmd - residual non-0 or status %x", rsp.status);
+		return GP_ERROR;
+	}
+	return GP_OK;
+}
+
+#define gp_port_send_scsi_cmd scsi_wrap_cmd
+
 static int
 usb_wrap_RDY(gp_port* dev, unsigned int type)
 {