diff --git a/README.md b/README.md
index bbb8a7f..e7780af 100644
--- a/README.md
+++ b/README.md
@@ -214,7 +214,9 @@ As <options> you can use:
     --nodeviceexit if no wmbus devices are found, then exit immediately
     --oneshot wait for an update from each meter, then quit
     --resetafter=<time> reset the wmbus dongle regularly, default is 23h
-    --selectfields=id,timestamp,total_m3 select fields to be printed
+    --addfields=timestamp_ut add the timestamp_ut field to be printed (--listfields=<meter> to list available fields)
+    --selectfields=id,timestamp,total_m3 select only these fields to be printed (--listfields=<meter> to list available fields)
+      addfields and selectfields are mutually exclusive.
     --separator=<c> change field separator to c
     --shell=<cmdline> invokes cmdline with env variables containing the latest reading
     --silent do not print informational messages nor warnings
@@ -461,6 +463,18 @@ wmbusmeters --format=fields --selectfields=id,total_m3 /dev/ttyUSB0:im871a Green
 33333333;9999.099
 ```
 
+Instead of selecting a subset you can add fields, such as: timestamp_ut, timestamp_utc, timestamp_lt
+and extra constant fields added using --field_xxx=yyy.
+
+```shell
+wmbusmeters --format=fields --field_city=Stockholm --addfields=timestamp_ut,city /dev/ttyUSB0:im871a GreenhouseWater multical21:c1 33333333 NOKEY
+```
+
+```
+GreenhouseTapWater;33333333;9999.099;77.712;0.000;11;31;;2018-03-05 12:10.24;1627855621,Stockholm
+```
+
+
 You can list all available fields for a meter: `wmbusmeters --listfields=multical21`
 
 You can list all meters: `wmbusmeters --listmeters`
diff --git a/src/cmdline.cc b/src/cmdline.cc
index 0756a0a..f175a65 100644
--- a/src/cmdline.cc
+++ b/src/cmdline.cc
@@ -277,6 +277,17 @@ shared_ptr<Configuration> parseCommandLine(int argc, char **argv) {
             i++;
             continue;
         }
+        if (!strncmp(argv[i], "--addfields=", 12)) {
+            if (strlen(argv[i]) > 12)
+            {
+                string s = string(argv[i]+12);
+                handleAddedFields(c, s);
+            } else {
+                error("You must supply fields to be added.\n");
+            }
+            i++;
+            continue;
+        }
 
         if (!strncmp(argv[i], "--separator=", 12)) {
             if (!c->fields) {
diff --git a/src/config.cc b/src/config.cc
index 7821edb..ea983a8 100644
--- a/src/config.cc
+++ b/src/config.cc
@@ -554,6 +554,11 @@ void handleLogTimestamps(Configuration *c, string ts)
 
 void handleSelectedFields(Configuration *c, string s)
 {
+    if (c->added_fields.size() > 0)
+    {
+        warning("(warning) addfields already used! Ignoring addfields %s", s);
+        return;
+    }
     char buf[s.length()+1];
     strcpy(buf, s.c_str());
     char *saveptr {};
@@ -567,6 +572,11 @@ void handleSelectedFields(Configuration *c, string s)
 
 void handleAddedFields(Configuration *c, string s)
 {
+    if (c->selected_fields.size() > 0)
+    {
+        warning("(warning) selectfields already used! Ignoring selectfields %s", s);
+        return;
+    }
     char buf[s.length()+1];
     strcpy(buf, s.c_str());
     char *saveptr {};
diff --git a/src/meters.cc b/src/meters.cc
index 82fc069..61dcd3d 100644
--- a/src/meters.cc
+++ b/src/meters.cc
@@ -276,8 +276,8 @@ MeterCommonImplementation::MeterCommonImplementation(MeterInfo &mi,
     for (auto s : mi.shells) {
         addShell(s);
     }
-    for (auto j : mi.jsons) {
-        addJson(j);
+    for (auto j : mi.extra_constant_fields) {
+        addExtraConstantField(j);
     }
 }
 
@@ -294,9 +294,9 @@ void MeterCommonImplementation::addShell(string cmdline)
     shell_cmdlines_.push_back(cmdline);
 }
 
-void MeterCommonImplementation::addJson(string json)
+void MeterCommonImplementation::addExtraConstantField(string ecf)
 {
-    jsons_.push_back(json);
+    extra_constant_fields_.push_back(ecf);
 }
 
 vector<string> &MeterCommonImplementation::shellCmdlines()
@@ -304,9 +304,9 @@ vector<string> &MeterCommonImplementation::shellCmdlines()
     return shell_cmdlines_;
 }
 
-vector<string> &MeterCommonImplementation::additionalJsons()
+vector<string> &MeterCommonImplementation::meterExtraConstantFields()
 {
-    return jsons_;
+    return extra_constant_fields_;
 }
 
 MeterDriver MeterCommonImplementation::driver()
@@ -584,7 +584,7 @@ void MeterCommonImplementation::triggerUpdate(Telegram *t)
     t->handled = true;
 }
 
-string concatAllFields(Meter *m, Telegram *t, char c, vector<Print> &prints, vector<Unit> &cs, bool hr)
+string concatAllFields(Meter *m, Telegram *t, char c, vector<Print> &prints, vector<Unit> &cs, bool hr, vector<string> *added_fields)
 {
     string s;
     s = "";
@@ -624,11 +624,11 @@ string concatAllFields(Meter *m, Telegram *t, char c, vector<Print> &prints, vec
 }
 
 string concatFields(Meter *m, Telegram *t, char c, vector<Print> &prints, vector<Unit> &cs, bool hr,
-                    vector<string> *selected_fields)
+                    vector<string> *selected_fields, vector<string> *added_fields)
 {
     if (selected_fields == NULL || selected_fields->size() == 0)
     {
-        return concatAllFields(m, t, c, prints, cs, hr);
+        return concatAllFields(m, t, c, prints, cs, hr, added_fields);
     }
     string s;
     s = "";
@@ -776,12 +776,12 @@ void MeterCommonImplementation::printMeter(Telegram *t,
                                            string *fields, char separator,
                                            string *json,
                                            vector<string> *envs,
-                                           vector<string> *more_json,
+                                           vector<string> *extra_constant_fields,
                                            vector<string> *selected_fields,
                                            vector<string> *added_fields)
 {
-    *human_readable = concatFields(this, t, '\t', prints_, conversions_, true, selected_fields);
-    *fields = concatFields(this, t, separator, prints_, conversions_, false, selected_fields);
+    *human_readable = concatFields(this, t, '\t', prints_, conversions_, true, selected_fields, added_fields);
+    *fields = concatFields(this, t, separator, prints_, conversions_, false, selected_fields, added_fields);
 
     string media;
     if (t->tpl_id_found)
@@ -838,15 +838,15 @@ void MeterCommonImplementation::printMeter(Telegram *t,
         s += "\"device\":\""+t->about.device+"\",";
         s += "\"rssi_dbm\":"+to_string(t->about.rssi_dbm);
     }
-    for (string add_json : additionalJsons())
+    for (string extra_field : meterExtraConstantFields())
     {
         s += ",";
-        s += makeQuotedJson(add_json);
+        s += makeQuotedJson(extra_field);
     }
-    for (string add_json : *more_json)
+    for (string extra_field : *extra_constant_fields)
     {
         s += ",";
-        s += makeQuotedJson(add_json);
+        s += makeQuotedJson(extra_field);
     }
     s += "}";
     *json = s;
@@ -901,13 +901,13 @@ void MeterCommonImplementation::printMeter(Telegram *t,
 
     // If the configuration has supplied json_address=Roodroad 123
     // then the env variable METER_address will available and have the content "Roodroad 123"
-    for (string add_json : additionalJsons())
+    for (string add_json : meterExtraConstantFields())
     {
         envs->push_back(string("METER_")+add_json);
     }
-    for (string add_json : *more_json)
+    for (string extra_field : *extra_constant_fields)
     {
-        envs->push_back(string("METER_")+add_json);
+        envs->push_back(string("METER_")+extra_field);
     }
 }
 
diff --git a/src/meters.h b/src/meters.h
index 38c2f6a..b494bb2 100644
--- a/src/meters.h
+++ b/src/meters.h
@@ -137,7 +137,7 @@ struct MeterInfo
     LinkModeSet link_modes;
     int bps {};     // For mbus communication you need to know the baud rate.
     vector<string> shells;
-    vector<string> jsons; // Additional static jsons that are added to each message.
+    vector<string> extra_constant_fields; // Additional static fields that are added to each message.
     vector<Unit> conversions; // Additional units desired in json.
 
     // If this is a meter that needs to be polled.
@@ -161,7 +161,7 @@ struct MeterInfo
         idsc = toIdsCommaSeparated(ids);
         key = k;
         shells = s;
-        jsons = j;
+        extra_constant_fields = j;
         link_modes = lms;
         bps = baud;
     }
@@ -175,7 +175,7 @@ struct MeterInfo
         idsc = "";
         key = "";
         shells.clear();
-        jsons.clear();
+        extra_constant_fields.clear();
         link_modes.clear();
         bps = 0;
     }
diff --git a/src/meters_common_implementation.h b/src/meters_common_implementation.h
index e3fe748..0fe480a 100644
--- a/src/meters_common_implementation.h
+++ b/src/meters_common_implementation.h
@@ -66,9 +66,9 @@ protected:
     void setExpectedTPLSecurityMode(TPLSecurityMode tsm);
     void addConversions(std::vector<Unit> cs);
     void addShell(std::string cmdline);
-    void addJson(std::string json);
+    void addExtraConstantField(std::string ecf);
     std::vector<std::string> &shellCmdlines();
-    std::vector<std::string> &additionalJsons();
+    std::vector<std::string> &meterExtraConstantFields();
     void addLinkMode(LinkMode lm);
     // Print with the default unit for this quantity.
     void addPrint(string vname, Quantity vquantity,
@@ -110,7 +110,7 @@ private:
     time_t datetime_of_update_ {};
     LinkModeSet link_modes_ {};
     vector<string> shell_cmdlines_;
-    vector<string> jsons_;
+    vector<string> extra_constant_fields_;
 
 protected:
     std::map<std::string,std::pair<int,std::string>> values_;
diff --git a/wmbusmeters.1 b/wmbusmeters.1
index a94ddbc..382a376 100644
--- a/wmbusmeters.1
+++ b/wmbusmeters.1
@@ -43,7 +43,7 @@ mqtt_publish) sent to a REST API (eg curl) or store it in a database
 
 \fB\--ignoreduplicates\fR=<bool> ignore duplicate telegrams, remember the last 10 telegrams. Default is true.
 
-\fB\--json_xxx=yyy\fR always add "xxx"="yyy" to the json output and add shell env METER_xxx=yyy
+\fB\--field_xxx=yyy\fR always add "xxx"="yyy" to the json output and add shell env METER_xxx=yyy The field xxx can also be selected or added using selectfields= and addfields=. Equivalent command is --json_xxx=yyy.
 
 \fB\--license\fR print GPLv3+ license
 
@@ -79,7 +79,9 @@ mqtt_publish) sent to a REST API (eg curl) or store it in a database
 
 \fB\--resetafter=\fR<time> reset the wmbus dongle regularly, default is 23h
 
-\fB\--selectfields=\fRid,timestamp,total_m3 select fields to be printed (--listfields=<meter> to list available fields)
+\fB\--addfields=\fRtimestamp_ut add the timestamp_ut field to be printed (--listfields=<meter> to list available fields)
+
+\fB\--selectfields=\fRid,timestamp,total_m3 select only these fields to be printed (--listfields=<meter> to list available fields)
 
 \fB\--separator=\fR<c> change field separator to c