--- a/tool/CommandGraph.cpp	Fri Mar 03 16:36:00 2017 +0100
+++ b/tool/CommandGraph.cpp	Fri Mar 03 16:49:13 2017 +0100
@@ -29,6 +29,7 @@
 
 #include <iostream>
 #include <map>
+#include <algorithm>
 using namespace std;
 
 #include "CommandGraph.h"
@@ -47,7 +48,9 @@
 {
     stringstream str;
 
-    str << binaryBaseName << " " << getName() << " [OPTIONS]" << endl
+    str
+        << binaryBaseName << " " << getName() << " [OPTIONS]" << endl
+        << binaryBaseName << " " << getName() << " [OPTIONS] <INFO>" << endl
         << endl
         << getBriefDescription() << endl
         << endl
@@ -58,19 +61,42 @@
         << endl
         << "  ethercat graph | dot -Tsvg > bus.svg" << endl
         << endl
-        << "See 'man dot' for more information." << endl;
+        << "See 'man dot' for more information." << endl
+        << endl
+        << "Additional information at edges and nodes is selected via" << endl
+        << "the first argument:" << endl
+        << "  DC  - DC timing" << endl
+        << "  CRC - CRC error register information" << endl
+        << endl;
 
     return str.str();
 }
 
 /****************************************************************************/
 
+enum Info {
+    None,
+    DC,
+    CRC
+};
+
+#define REG_SIZE (20)
+
+struct CrcInfo {
+    unsigned int crc[EC_MAX_PORTS];
+    unsigned int phy[EC_MAX_PORTS];
+    unsigned int fwd[EC_MAX_PORTS];
+    unsigned int lnk[EC_MAX_PORTS];
+};
+
 void CommandGraph::execute(const StringVector &args)
 {
+    Info info = None;
     ec_ioctl_master_t master;
-    unsigned int i;
     typedef vector<ec_ioctl_slave_t> SlaveVector;
     SlaveVector slaves;
+    typedef vector<CrcInfo> CrcInfoVector;
+    CrcInfoVector crcInfos;
     ec_ioctl_slave_t slave;
     SlaveVector::const_iterator si;
     map<int, string> portMedia;
@@ -84,19 +110,64 @@
     portMedia[EC_PORT_EBUS] = "EBUS";
     mediaWeights[EC_PORT_EBUS] = 5;
 
-    if (args.size()) {
+    if (args.size() > 1) {
         stringstream err;
-        err << "'" << getName() << "' takes no arguments!";
+        err << "'" << getName() << "' takes either one or no arguments!";
         throwInvalidUsageException(err);
     }
 
+    if (args.size() == 1) {
+        string arg = args[0];
+        transform(arg.begin(), arg.end(),
+                arg.begin(), (int (*) (int)) std::toupper);
+        if (arg == "DC") {
+            info = DC;
+        }
+        else if (arg == "CRC") {
+            info = CRC;
+        }
+        else {
+            stringstream err;
+            err << "Unknown argument \"" << args[0] << "\"!";
+            throwInvalidUsageException(err);
+        }
+    }
+
     MasterDevice m(getSingleMasterIndex());
     m.open(MasterDevice::Read);
     m.getMaster(&master);
 
-    for (i = 0; i < master.slave_count; i++) {
+    for (unsigned int i = 0; i < master.slave_count; i++) {
         m.getSlave(&slave, i);
         slaves.push_back(slave);
+
+    }
+
+    if (info == CRC) {
+        uint8_t data[REG_SIZE];
+        ec_ioctl_slave_reg_t io;
+        io.emergency = 0;
+        io.address = 0x0300;
+        io.size = REG_SIZE;
+        io.data = data;
+
+        for (unsigned int i = 0; i < master.slave_count; i++) {
+            io.slave_position = i;
+            try {
+                m.readReg(&io);
+            } catch (MasterDeviceException &e) {
+                throw e;
+            }
+
+            CrcInfo crcInfo;
+            for (int port = 0; port < EC_MAX_PORTS; port++) {
+                crcInfo.crc[port] = io.data[ 0 + port * 2];
+                crcInfo.phy[port] = io.data[ 1 + port * 2];
+                crcInfo.fwd[port] = io.data[ 8 + port];
+                crcInfo.lnk[port] = io.data[16 + port];
+            }
+            crcInfos.push_back(crcInfo);
+        }
     }
 
     cout << "/* EtherCAT bus graph. Generated by 'ethercat graph'. */" << endl
@@ -134,7 +205,7 @@
             << " / " << alias << ":" << pos;
         if (string(si->order).size())
             cout << "\\n" << si->order;
-        if (si->dc_supported) {
+        if (info == DC && si->dc_supported) {
             cout << "\\nDC: ";
             if (si->has_dc_system_time) {
                 switch (si->dc_range) {
@@ -154,33 +225,46 @@
         }
         cout << "\"]" << endl;
 
-        for (i = 1; i < EC_MAX_PORTS; i++) {
-            uint16_t next_pos = si->ports[i].next_slave;
-            ec_ioctl_slave_t *next = NULL;
-
-            if (next_pos == 0xffff)
+
+        for (int port = 1; port < EC_MAX_PORTS; port++) {
+            uint16_t next_pos = si->ports[port].next_slave;
+
+            if (next_pos == 0xffff) {
                 continue;
-
-            if (next_pos < slaves.size()) {
-                next = &slaves[next_pos];
-            } else {
+            }
+
+            if (next_pos >= slaves.size()) {
                 cerr << "Invalid next slave pointer." << endl;
-            }
+                continue;
+            }
+
+            ec_ioctl_slave_t *next = &slaves[next_pos];
 
             cout << "    slave" << si->position << " -- "
-                << "slave" << next_pos << " [taillabel=\"" << i;
-
-            if (si->dc_supported) {
-                cout << " [" << si->ports[i].delay_to_next_dc << "]";
-            }
+                << "slave" << next_pos << " [taillabel=\"" << port;
+
+            if (info == DC && si->dc_supported) {
+                cout << " [" << si->ports[port].delay_to_next_dc << "]";
+            }
+            if (info == CRC) {
+                CrcInfo *crcInfo = &crcInfos[si->position];
+                cout << " [" << crcInfo->crc[port] << "/"
+                    << crcInfo->fwd[port] << "]";
+            }
+
             cout << "\",headlabel=\"0";
 
-            if (next && next->dc_supported) {
+            if (info == DC && next->dc_supported) {
                 cout << " [" << next->ports[0].delay_to_next_dc << "]";
             }
+            if (info == CRC) {
+                CrcInfo *crcInfo = &crcInfos[next_pos];
+                cout << " [" << crcInfo->crc[0] << "/"
+                    << crcInfo->fwd[0] << "]";
+            }
             cout << "\"";
 
-            mi = portMedia.find(si->ports[i].desc);
+            mi = portMedia.find(si->ports[port].desc);
             if (mi == portMedia.end() && next) {
                 /* Try medium of next-hop slave. */
                 mi = portMedia.find(next->ports[0].desc);
@@ -189,7 +273,7 @@
             if (mi != portMedia.end())
                 cout << ",label=\"" << mi->second << "\"";
 
-            wi = mediaWeights.find(si->ports[i].desc);
+            wi = mediaWeights.find(si->ports[port].desc);
             if (wi != mediaWeights.end())
                 cout << ",weight=\"" << wi->second << "\"";