diff --git a/slsDetectorSoftware/generator/Caller.in.h b/slsDetectorSoftware/generator/Caller.in.h
index f7128620e..e18dec02c 100644
--- a/slsDetectorSoftware/generator/Caller.in.h
+++ b/slsDetectorSoftware/generator/Caller.in.h
@@ -54,6 +54,9 @@ class Caller {
         return ToString(value, unit);
     }
 
+    std::string OutString(const Result<defs::Hz> &value,
+                          const std::string &unit);
+
     std::vector<std::string> getAllCommands();
     std::map<std::string, std::string> GetDeprecatedCommands();
     std::string list(int action);
@@ -96,6 +99,7 @@ class Caller {
     defs::dacIndex parseDacIndex(int argIndex, bool isCtb);
     bool parseMV(int argIndex);
     defs::powerIndex parsePowerIndex(int argIndex);
+    defs::FrequencyUnit parseFrequencyUnit(const std::string &s);
 
     FunctionMap functions{
         {"list", &Caller::list},
diff --git a/slsDetectorSoftware/src/Caller.h b/slsDetectorSoftware/src/Caller.h
index ce9e7cc93..d35ffe569 100644
--- a/slsDetectorSoftware/src/Caller.h
+++ b/slsDetectorSoftware/src/Caller.h
@@ -54,6 +54,9 @@ class Caller {
         return ToString(value, unit);
     }
 
+    std::string OutString(const Result<defs::Hz> &value,
+                          const std::string &unit);
+
     std::vector<std::string> getAllCommands();
     std::map<std::string, std::string> GetDeprecatedCommands();
     std::string list(int action);
@@ -421,6 +424,7 @@ class Caller {
     defs::dacIndex parseDacIndex(int argIndex, bool isCtb);
     bool parseMV(int argIndex);
     defs::powerIndex parsePowerIndex(int argIndex);
+    defs::FrequencyUnit parseFrequencyUnit(const std::string &s);
 
     FunctionMap functions{
         {"list", &Caller::list},
diff --git a/slsDetectorSoftware/src/CallerSpecial.cpp b/slsDetectorSoftware/src/CallerSpecial.cpp
index cf339ee5d..50cd1e72d 100644
--- a/slsDetectorSoftware/src/CallerSpecial.cpp
+++ b/slsDetectorSoftware/src/CallerSpecial.cpp
@@ -11,6 +11,14 @@
 namespace sls {
 // some helper functions to print
 
+std::string Caller::OutString(const Result<defs::Hz> &value,
+                              const std::string &unit) {
+    auto u = parseFrequencyUnit(unit);
+    if (value.equal())
+        return ToString(value.front(), u);
+    return ToString(value, u);
+}
+
 std::vector<std::string> Caller::getAllCommands() {
     std::vector<std::string> ret;
     for (auto it : functions)
@@ -2105,4 +2113,21 @@ std::string Caller::powervalues(int action) {
     return os.str();
 }
 
+defs::FrequencyUnit Caller::parseFrequencyUnit(const std::string &unit) {
+    auto unitLower = [&] {
+        std::string result = unit;
+        std::transform(result.begin(), result.end(), result.begin(),
+                       [](unsigned char c) { return std::tolower(c); });
+        return result;
+    }();
+    if (unitLower == "hz")
+        return defs::FrequencyUnit::Hz;
+    if (unitLower == "khz")
+        return defs::FrequencyUnit::kHz;
+    if (unitLower == "mhz")
+        return defs::FrequencyUnit::MHz;
+
+    throw std::runtime_error("Unknown frequency unit: " + unit);
+}
+
 } // namespace sls
\ No newline at end of file
diff --git a/slsSupportLib/include/sls/ToString.h b/slsSupportLib/include/sls/ToString.h
index 569e84a54..7035f9c38 100644
--- a/slsSupportLib/include/sls/ToString.h
+++ b/slsSupportLib/include/sls/ToString.h
@@ -109,42 +109,10 @@ ToString(From t) {
 }
 
 /** Convert frequency with specified output unit */
-template <typename T>
-typename std::enable_if<is_frequency<T>::value, std::string>::type
-ToString(T f, const std::string &unit) {
-    double val = static_cast<double>(f.value);
-
-    auto unitLower = [&] {
-        std::string result = unit;
-        std::transform(result.begin(), result.end(), result.begin(),
-                       [](unsigned char c) { return std::tolower(c); });
-        return result;
-    }();
-    std::ostringstream os;
-    if (unitLower == "hz")
-        os << val << unit;
-    else if (unitLower == "khz")
-        os << val / (static_cast<double>(1e3)) << unit;
-    else if (unitLower == "mhz")
-        os << val / (static_cast<double>(1e6)) << unit;
-    else
-        throw std::runtime_error("Unknown unit: " + unit);
-    return os.str();
-}
+std::string ToString(defs::Hz f, defs::FrequencyUnit unit);
 
 /** Convert frequency automatically selecting the unit */
-template <typename From>
-typename std::enable_if<is_frequency<From>::value, std::string>::type
-ToString(From f) {
-    int val = f.value;
-    if (val < 1e3) {
-        return ToString(f, "Hz");
-    } else if (val < 1e6) {
-        return ToString(f, "kHz");
-    } else {
-        return ToString(f, "MHz");
-    }
-}
+std::string ToString(defs::Hz f);
 
 /** Conversion of floating point values, removes trailing zeros*/
 template <typename T>
@@ -317,6 +285,22 @@ ToString(const T &container, const std::string &unit) {
     return os.str();
 }
 
+/** Container and specified unit, call ToString(value, FrequencyUnit) */
+template <typename T>
+typename std::enable_if<is_container<T>::value, std::string>::type
+ToString(const T &container, defs::FrequencyUnit unit) {
+    std::ostringstream os;
+    os << '[';
+    if (!container.empty()) {
+        auto it = container.cbegin();
+        os << ToString(*it++, unit);
+        while (it != container.cend())
+            os << ", " << ToString(*it++, unit);
+    }
+    os << ']';
+    return os.str();
+}
+
 template <typename T, std::enable_if_t<sls::is_duration<T>::value, int> = 0>
 T StringTo(const std::string &t, const std::string &unit) {
     double tval{0};
diff --git a/slsSupportLib/include/sls/sls_detector_defs.h b/slsSupportLib/include/sls/sls_detector_defs.h
index 79aec83a1..9ab24a16d 100644
--- a/slsSupportLib/include/sls/sls_detector_defs.h
+++ b/slsSupportLib/include/sls/sls_detector_defs.h
@@ -219,6 +219,8 @@ class slsDetectorDefs {
         }
     };
 
+    enum class FrequencyUnit { Hz, kHz, MHz };
+
 #endif
     enum frameDiscardPolicy {
         NO_DISCARD,
diff --git a/slsSupportLib/src/ToString.cpp b/slsSupportLib/src/ToString.cpp
index f8ac4c684..26c94f2b2 100644
--- a/slsSupportLib/src/ToString.cpp
+++ b/slsSupportLib/src/ToString.cpp
@@ -739,6 +739,36 @@ std::string ToString(const defs::collectionMode s) {
 
 const std::string &ToString(const std::string &s) { return s; }
 
+std::string ToString(defs::Hz f, defs::FrequencyUnit unit) {
+    double val = static_cast<double>(f.value);
+    std::ostringstream os;
+    switch (unit) {
+    case defs::FrequencyUnit::Hz:
+        os << val << "Hz";
+        break;
+    case defs::FrequencyUnit::kHz:
+        os << val / (static_cast<double>(1e3)) << "kHz";
+        break;
+    case defs::FrequencyUnit::MHz:
+        os << val / (static_cast<double>(1e6)) << "MHz";
+        break;
+    default:
+        throw std::runtime_error("Unknown frequency unit");
+    }
+    return os.str();
+}
+
+std::string ToString(defs::Hz f) {
+    int val = f.value;
+    if (val < 1e3) {
+        return ToString(f, defs::FrequencyUnit::Hz);
+    } else if (val < 1e6) {
+        return ToString(f, defs::FrequencyUnit::kHz);
+    } else {
+        return ToString(f, defs::FrequencyUnit::MHz);
+    }
+}
+
 template <> defs::detectorType StringTo(const std::string &s) {
     if (s == "Eiger")
         return defs::EIGER;
diff --git a/slsSupportLib/tests/test-ToString.cpp b/slsSupportLib/tests/test-ToString.cpp
index a7ef24c7f..0c35bdfc0 100644
--- a/slsSupportLib/tests/test-ToString.cpp
+++ b/slsSupportLib/tests/test-ToString.cpp
@@ -80,9 +80,9 @@ TEST_CASE("conversion from frequency to string", "[support]") {
     REQUIRE(ToString(defs::Hz(150)) == "150Hz");
     REQUIRE(ToString(defs::Hz(1500)) == "1.5kHz");
     REQUIRE(ToString(defs::Hz(1500000)) == "1.5MHz");
-    REQUIRE(ToString(defs::Hz(150), "Hz") == "150Hz");
-    REQUIRE(ToString(defs::Hz(150), "kHz") == "0.15kHz");
-    REQUIRE(ToString(defs::Hz(150), "MHz") == "0.00015MHz");
+    REQUIRE(ToString(defs::Hz(150), defs::FrequencyUnit::Hz) == "150Hz");
+    REQUIRE(ToString(defs::Hz(150), defs::FrequencyUnit::kHz) == "0.15kHz");
+    REQUIRE(ToString(defs::Hz(150), defs::FrequencyUnit::MHz) == "0.00015MHz");
 }
 
 TEST_CASE("Convert vector of time", "[support]") {