diff --git a/slsDetectorSoftware/tests/CMakeLists.txt b/slsDetectorSoftware/tests/CMakeLists.txt
index f84c00c3d..681a6801d 100755
--- a/slsDetectorSoftware/tests/CMakeLists.txt
+++ b/slsDetectorSoftware/tests/CMakeLists.txt
@@ -19,7 +19,7 @@ target_sources(tests PRIVATE
     ${CMAKE_CURRENT_SOURCE_DIR}/Caller/test-Caller-global.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/Caller/test-Caller-acquire.cpp
 
-    ${CMAKE_CURRENT_SOURCE_DIR}/master_file/Readers.cpp
+#    ${CMAKE_CURRENT_SOURCE_DIR}/master_file/Readers.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/Caller/test-Caller-master-attributes.cpp
 
     
diff --git a/slsDetectorSoftware/tests/Caller/test-Caller-master-attributes.cpp b/slsDetectorSoftware/tests/Caller/test-Caller-master-attributes.cpp
index abdcbb6b5..5c16581a1 100644
--- a/slsDetectorSoftware/tests/Caller/test-Caller-master-attributes.cpp
+++ b/slsDetectorSoftware/tests/Caller/test-Caller-master-attributes.cpp
@@ -1,7 +1,10 @@
 // SPDX-License-Identifier: LGPL-3.0-or-other
 // Copyright (C) 2021 Contributors to the SLS Detector Package
 #include "master_file/Context.h"
-#include "master_file/Readers.h"
+#include "master_file/ReadersJson.h"
+#ifdef HDF5C
+#include "master_file/ReadersH5.h"
+#endif
 
 #include "Caller.h"
 #include "MasterAttributes.h"
@@ -23,7 +26,6 @@
 
 #ifdef HDF5C
 #include "H5Cpp.h"
-const std::string HDF5_GROUP = "/entry/instrument/detector/";
 #endif
 
 namespace sls {
@@ -41,40 +43,26 @@ inline bool operator==(sls::ns lhs, sls::ns rhs) {
     return lhs.count() == rhs.count();
 }
 
-/** test parameter in file */
-template <typename T>
-void test_json_parameter(const Document &doc, const std::string &name,
-                         const T &expected) {
-    REQUIRE(doc.HasMember(name.c_str()));
-    T retval{};
-    mf::read_from_json(doc, name, retval);
-    REQUIRE(retval == expected);
-}
-#ifdef HDF5C
-template <typename T>
-void test_h5_dataset(const std::string &name, const T &expected) {
-    REQUIRE(h5ctx.has_value());
-    auto dataset = h5ctx->file.openDataSet(HDF5_GROUP + name);
-    T retval{};
-    mf::read_from_h5_dataset(dataset, name, retval);
-    // auto retval = mf::read<mf::H5Doc, T>(mf::H5Doc{dataset}, name);
-    REQUIRE(retval == expected);
-}
-#endif
-
 template <typename T>
 void check_master_file(const std::optional<Document> &doc,
                        const std::string &name, const T &expected) {
-    if (doc.has_value()) {
+    if (doc) {
         const auto &d = *doc;
-        test_json_parameter(d, name, expected);
+        REQUIRE(d.HasMember(name.c_str()));
+        mf::JsonContext ctx{d};
+        auto retval = mf::read<mf::JsonContext, T>(ctx, name);
+        REQUIRE(retval == expected);
     } else {
 #ifdef HDF5C
         if (!h5ctx.has_value()) {
             throw sls::RuntimeError("HDF5 file is not opened for testing " +
                                     name);
         }
-        test_h5_dataset(name, expected);
+        REQUIRE(h5ctx.has_value());
+        // require hdf5 has dataset with this name
+        // REQUIRE(h5ctx.)
+        auto retval = mf::read<mf::H5Context, T>(*h5ctx, name);
+        REQUIRE(retval == expected);
 #else
         throw sls::RuntimeError("Document is not available for testing " +
                                 name);
@@ -86,12 +74,12 @@ void test_master_file_version(const Detector &det,
                               const std::optional<Document> &doc) {
     // different values for json and hdf5
     // hdf5 version in atttribute and not dataset
-    double retval{};
-    std::string name = MasterAttributes::N_VERSION.data();
-    if (doc.has_value()) {
+    const auto name = MasterAttributes::N_VERSION.data();
+    if (doc) {
         const auto &d = *doc;
-        REQUIRE(d.HasMember(MasterAttributes::N_VERSION.data()));
-        mf::read_from_json(d, name, retval);
+        REQUIRE(d.HasMember(name));
+        mf::JsonContext ctx{d};
+        double retval = mf::read<mf::JsonContext, double>(ctx, name);
         REQUIRE(retval == BINARY_WRITER_VERSION);
     } else {
 #ifdef HDF5C
@@ -101,6 +89,7 @@ void test_master_file_version(const Detector &det,
         }
         auto attr =
             h5ctx->file.openAttribute(MasterAttributes::N_VERSION.data());
+        double retval{};
         attr.read(attr.getDataType(), &retval);
         REQUIRE(retval == HDF5_WRITER_VERSION);
 #else
diff --git a/slsDetectorSoftware/tests/master_file/Context.h b/slsDetectorSoftware/tests/master_file/Context.h
index e5fd13048..bbf37a31b 100644
--- a/slsDetectorSoftware/tests/master_file/Context.h
+++ b/slsDetectorSoftware/tests/master_file/Context.h
@@ -13,7 +13,7 @@
 namespace sls::test::master_file {
 
 struct JsonContext {
-    rapidjson::Document doc;
+    const rapidjson::Document &doc;
 };
 #ifdef HDF5C
 struct H5Context {
diff --git a/slsDetectorSoftware/tests/master_file/Readers.cpp b/slsDetectorSoftware/tests/master_file/Readers.cpp
deleted file mode 100644
index d9e14745c..000000000
--- a/slsDetectorSoftware/tests/master_file/Readers.cpp
+++ /dev/null
@@ -1,272 +0,0 @@
-// SPDX-License-Identifier: LGPL-3.0-or-other
-// Copyright (C) 2021 Contributors to the SLS Detector Package
-#include "Readers.h"
-
-#include "sls/ToString.h"
-
-namespace sls::test::master_file {
-
-/* --scalar reads-- */
-
-/** std::string */
-void read_from_json(const Document &doc, const std::string &name,
-                    std::string &out) {
-    out = doc[name.c_str()].GetString();
-}
-#ifdef HDF5C
-void read_from_h5_dataset(const H5::DataSet &ds, const std::string &name,
-                          std::string &out) {
-    ds.read(out, ds.getStrType());
-}
-#endif
-
-/** int */
-void read_from_json(const Document &doc, const std::string &name, int &out) {
-    out = doc[name.c_str()].GetInt();
-}
-#ifdef HDF5C
-void read_from_h5_dataset(const H5::DataSet &ds, const std::string &name,
-                          int &out) {
-    ds.read(&out, H5::PredType::NATIVE_INT);
-}
-#endif
-
-/** uint32_t */
-void read_from_json(const Document &doc, const std::string &name,
-                    uint32_t &out) {
-    out = doc[name.c_str()].GetUint();
-}
-#ifdef HDF5C
-void read_from_h5_dataset(const H5::DataSet &ds, const std::string &name,
-                          uint32_t &out) {
-    ds.read(&out, H5::PredType::STD_U32LE);
-}
-#endif
-
-/** uint64_t */
-void read_from_json(const Document &doc, const std::string &name,
-                    uint64_t &out) {
-    out = doc[name.c_str()].GetUint64();
-}
-#ifdef HDF5C
-void read_from_h5_dataset(const H5::DataSet &ds, const std::string &name,
-                          uint64_t &out) {
-    ds.read(&out, H5::PredType::STD_U64LE);
-}
-#endif
-
-/** double */
-void read_from_json(const Document &doc, const std::string &name, double &out) {
-    out = doc[name.c_str()].GetDouble();
-}
-#ifdef HDF5C
-void read_from_h5_dataset(const H5::DataSet &ds, const std::string &name,
-                          double &out) {
-    ds.read(&out, H5::PredType::NATIVE_DOUBLE);
-}
-#endif
-
-/** vector<string> */
-/** std::vector<int64_t> */
-void read_from_json(const Document &doc, const std::string &name,
-                    std::vector<int64_t> &out) {
-    for (const auto &item : doc[name.c_str()].GetArray()) {
-        out.push_back(item.GetInt64());
-    }
-}
-#ifdef HDF5C
-void read_from_h5_dataset(const H5::DataSet &ds, const std::string &name,
-                          std::vector<int64_t> &out) {
-    H5::DataSpace dataspace = ds.getSpace();
-    hsize_t dims[1];
-    dataspace.getSimpleExtentDims(dims);
-    out.resize(dims[0]);
-    ds.read(out.data(), H5::PredType::STD_I64LE);
-}
-#endif
-
-/* ---arrays/ maps--- */
-/** std::array<int, 3UL> */
-void read_from_json(const Document &doc, const std::string &name,
-                    std::array<int, 3UL> &out) {
-    const auto &json_values = doc[name.c_str()].GetArray();
-    auto len = json_values.Size();
-    if (len != 3) {
-        throw sls::RuntimeError("JSON array " + name + " has " +
-                                std::to_string(len) +
-                                " elements instead of 3.");
-    }
-    int index = 0;
-    for (const auto &item : json_values) {
-        out[index++] = item.GetInt();
-    }
-}
-#ifdef HDF5C
-void read_from_h5_dataset(const H5::DataSet &ds, const std::string &name,
-                          std::array<int, 3UL> &out) {
-    H5::DataSpace dataspace = ds.getSpace();
-    hsize_t dims[1];
-    dataspace.getSimpleExtentDims(dims);
-    auto len = dims[0];
-    if (len != 3) {
-        throw sls::RuntimeError("HDF5 dataset " + name + " has " +
-                                std::to_string(len) +
-                                " elements instead of 3.");
-    }
-    ds.read(out.data(), H5::PredType::NATIVE_INT);
-}
-#endif
-
-/* std::array<ns, 3UL> */
-void read_from_json(const Document &doc, const std::string &name,
-                    std::array<ns, 3UL> &out) {
-    const auto &json_values = doc[name.c_str()].GetArray();
-    auto len = json_values.Size();
-    if (len != 3) {
-        throw sls::RuntimeError("JSON array " + name + " has " +
-                                std::to_string(len) +
-                                " elements instead of 3.");
-    }
-    int index = 0;
-    for (const auto &item : json_values) {
-        std::string sval = item.GetString();
-        out[index++] = StringTo<ns>(sval);
-    }
-}
-#ifdef HDF5C
-void read_from_h5_dataset(const H5::DataSet &ds, const std::string &name,
-                          std::array<ns, 3UL> &out) {
-    H5::DataSpace dataspace = ds.getSpace();
-    hsize_t dims[1];
-    dataspace.getSimpleExtentDims(dims);
-    auto len = dims[0];
-    if (len != 3) {
-        throw sls::RuntimeError("HDF5 dataset " + name + " has " +
-                                std::to_string(len) +
-                                " elements instead of 3.");
-    }
-    std::vector<const char *> strValues(dims[0]);
-    ds.read(strValues.data(), ds.getStrType());
-    for (size_t i = 0; i < dims[0]; ++i) {
-        out[i] = StringTo<ns>(strValues[i]);
-    }
-}
-#endif
-
-/** std::map<std::string, std::string> */
-void read_from_json(const Document &doc, const std::string &name,
-                    std::map<std::string, std::string> &out) {
-    for (const auto &m : doc[name.c_str()].GetObject()) {
-        out[m.name.GetString()] = m.value.GetString();
-    }
-}
-#ifdef HDF5C
-void read_from_h5_dataset(const H5::DataSet &ds, const std::string &name,
-                          std::map<std::string, std::string> &out) {
-    H5::DataSpace dataspace = ds.getSpace();
-    hsize_t dims[1];
-    dataspace.getSimpleExtentDims(dims);
-    if (dims[0] == 0) {
-        return; // empty ds
-    }
-    auto strType = ds.getStrType();
-    H5::CompType mapType(sizeof(char *) * 2);
-    mapType.insertMember("key", 0, strType);
-    mapType.insertMember("value", sizeof(char *), strType);
-    struct KeyValue {
-        const char *key;
-        const char *value;
-    };
-    std::vector<KeyValue> kv_vector(dims[0]);
-    ds.read(kv_vector.data(), mapType);
-    for (const auto &kv : kv_vector) {
-        out[kv.key] = kv.value;
-    }
-}
-#endif
-
-/** complex types */
-/* std::vector<ROI> */
-void read_from_json(const Document &doc, const std::string &name,
-                    std::vector<defs::ROI> &out) {
-    for (const auto &item : doc[name.c_str()].GetArray()) {
-        defs::ROI r{};
-        r.xmin = item["xmin"].GetInt();
-        r.xmax = item["xmax"].GetInt();
-        r.ymin = item["ymin"].GetInt();
-        r.ymax = item["ymax"].GetInt();
-        out.push_back(r);
-    }
-}
-#ifdef HDF5C
-void read_from_h5_dataset(const H5::DataSet &ds, const std::string &name,
-                          std::vector<defs::ROI> &out) {
-    H5::DataSpace space = ds.getSpace();
-    hsize_t dims[1];
-    space.getSimpleExtentDims(dims);
-
-    H5::CompType type(sizeof(defs::ROI));
-    type.insertMember("xmin", HOFFSET(defs::ROI, xmin),
-                      H5::PredType::NATIVE_INT);
-    type.insertMember("xmax", HOFFSET(defs::ROI, xmax),
-                      H5::PredType::NATIVE_INT);
-    type.insertMember("ymin", HOFFSET(defs::ROI, ymin),
-                      H5::PredType::NATIVE_INT);
-    type.insertMember("ymax", HOFFSET(defs::ROI, ymax),
-                      H5::PredType::NATIVE_INT);
-
-    out.resize(dims[0]);
-    ds.read(out.data(), type);
-}
-#endif
-
-/** defs::xy */
-void read_from_json(const Document &doc, const std::string &name,
-                    defs::xy &out) {
-    out.x = doc[name.c_str()]["x"].GetInt();
-    out.y = doc[name.c_str()]["y"].GetInt();
-}
-#ifdef HDF5C
-void read_from_h5_dataset(const H5::DataSet &ds, const std::string &name,
-                          defs::xy &out) {
-    H5::CompType type(sizeof(defs::xy));
-    type.insertMember("x", HOFFSET(defs::xy, x), H5::PredType::NATIVE_INT);
-    type.insertMember("y", HOFFSET(defs::xy, y), H5::PredType::NATIVE_INT);
-    ds.read(&out, type);
-}
-#endif
-
-/** defs::scanParameters */
-void read_from_json(const Document &doc, const std::string &name,
-                    defs::scanParameters &out) {
-    const auto &s = doc[name.c_str()].GetObject();
-    out.enable = s["enable"].GetInt();
-    out.dacInd = static_cast<defs::dacIndex>(s["dacInd"].GetInt());
-    out.startOffset = s["start offset"].GetInt();
-    out.stopOffset = s["stop offset"].GetInt();
-    out.stepSize = s["step size"].GetInt();
-    out.dacSettleTime_ns = s["dac settle time ns"].GetInt64();
-}
-#ifdef HDF5C
-void read_from_h5_dataset(const H5::DataSet &ds, const std::string &name,
-                          defs::scanParameters &out) {
-    H5::CompType cType(sizeof(defs::scanParameters));
-    cType.insertMember("enable", HOFFSET(defs::scanParameters, enable),
-                       H5::PredType::NATIVE_INT);
-    cType.insertMember("dacInd", HOFFSET(defs::scanParameters, dacInd),
-                       H5::PredType::NATIVE_INT);
-    cType.insertMember("startOffset",
-                       HOFFSET(defs::scanParameters, startOffset),
-                       H5::PredType::NATIVE_INT);
-    cType.insertMember("stopOffset", HOFFSET(defs::scanParameters, stopOffset),
-                       H5::PredType::NATIVE_INT);
-    cType.insertMember("stepSize", HOFFSET(defs::scanParameters, stepSize),
-                       H5::PredType::NATIVE_INT);
-    cType.insertMember("dacSettleTime_ns",
-                       HOFFSET(defs::scanParameters, dacSettleTime_ns),
-                       H5::PredType::STD_I64LE);
-    ds.read(&out, cType);
-}
-#endif
-
-} // namespace sls::test::master_file
diff --git a/slsDetectorSoftware/tests/master_file/Readers.h b/slsDetectorSoftware/tests/master_file/Readers.h
index 84b160fb9..a9fbaa724 100644
--- a/slsDetectorSoftware/tests/master_file/Readers.h
+++ b/slsDetectorSoftware/tests/master_file/Readers.h
@@ -3,14 +3,10 @@
 #pragma once
 
 #include "Context.h"
-
-#ifdef HDF5C
-#include "H5Cpp.h"
-#endif
-
-#include <rapidjson/document.h>
+#include "sls/sls_detector_defs.h"
 
 namespace sls::test::master_file {
+
 template <typename Context, typename T> struct Reader;
 
 template <typename Context, typename T>
@@ -18,4 +14,13 @@ T read(const Context &ctx, const std::string &name) {
     return Reader<Context, T>::read(ctx, name);
 }
 
+inline void check_size(size_t actual, size_t expected, const std::string &name,
+                       const std::string &doc) {
+    if (actual != expected) {
+        throw sls::RuntimeError(
+            doc + " array " + name + " has " + std::to_string(actual) +
+            " elements instead of " + std::to_string(expected));
+    }
+}
+
 } // namespace sls::test::master_file
diff --git a/slsDetectorSoftware/tests/master_file/ReadersH5.cpp b/slsDetectorSoftware/tests/master_file/ReadersH5.cpp
deleted file mode 100644
index 647197b6b..000000000
--- a/slsDetectorSoftware/tests/master_file/ReadersH5.cpp
+++ /dev/null
@@ -1,25 +0,0 @@
-// SPDX-License-Identifier: LGPL-3.0-or-other
-// Copyright (C) 2021 Contributors to the SLS Detector Package
-
-#include "Readers.h"
-
-#ifdef HDF5C
-
-namespace sls::test::master_file {
-
-template <>
-struct Reader<H5Context, int> {
-
-    static int read(const H5Context& ctx,
-                    const std::string& name) {
-
-        auto ds = ctx.file.openDataSet(HDF5_GROUP + name);
-        int out{};
-        ds.read(&out, H5::PredType::NATIVE_INT);
-        return out;
-    }
-};
-
-} // namespace sls::test::master_file
-
-#endif
\ No newline at end of file
diff --git a/slsDetectorSoftware/tests/master_file/ReadersH5.h b/slsDetectorSoftware/tests/master_file/ReadersH5.h
new file mode 100644
index 000000000..c7690d394
--- /dev/null
+++ b/slsDetectorSoftware/tests/master_file/ReadersH5.h
@@ -0,0 +1,211 @@
+// SPDX-License-Identifier: LGPL-3.0-or-other
+// Copyright (C) 2021 Contributors to the SLS Detector Package
+#pragma once
+
+#include "Readers.h"
+#include "sls/sls_detector_defs.h"
+
+#ifdef HDF5C
+#include "H5Cpp.h"
+
+namespace sls::test::master_file {
+using ns = std::chrono::nanoseconds;
+
+const std::string HDF5_GROUP = "/entry/instrument/detector/";
+
+/* --scalar reads-- */
+template <> struct Reader<H5Context, int> {
+    static int read(const H5Context &ctx, const std::string &name) {
+        auto ds = ctx.file.openDataSet(HDF5_GROUP + name);
+        int out{};
+        ds.read(&out, H5::PredType::NATIVE_INT);
+        return out;
+    }
+};
+
+template <> struct Reader<H5Context, uint32_t> {
+    static uint32_t read(const H5Context &ctx, const std::string &name) {
+        auto ds = ctx.file.openDataSet(HDF5_GROUP + name);
+        uint32_t out{};
+        ds.read(&out, H5::PredType::STD_U32LE);
+        return out;
+    }
+};
+
+template <> struct Reader<H5Context, uint64_t> {
+    static uint64_t read(const H5Context &ctx, const std::string &name) {
+        auto ds = ctx.file.openDataSet(HDF5_GROUP + name);
+        uint64_t out{};
+        ds.read(&out, H5::PredType::STD_U64LE);
+        return out;
+    }
+};
+
+template <> struct Reader<H5Context, double> {
+    static double read(const H5Context &ctx, const std::string &name) {
+        auto ds = ctx.file.openDataSet(HDF5_GROUP + name);
+        double out{};
+        ds.read(&out, H5::PredType::NATIVE_DOUBLE);
+        return out;
+    }
+};
+
+template <> struct Reader<H5Context, std::string> {
+    static std::string read(const H5Context &ctx, const std::string &name) {
+        auto ds = ctx.file.openDataSet(HDF5_GROUP + name);
+        std::string out{};
+        ds.read(out, ds.getStrType());
+        return out;
+    }
+};
+
+/** complex types */
+template <> struct Reader<H5Context, defs::xy> {
+    static defs::xy read(const H5Context &ctx, const std::string &name) {
+        auto ds = ctx.file.openDataSet(HDF5_GROUP + name);
+        // define type
+        H5::CompType type(sizeof(defs::xy));
+        type.insertMember("x", HOFFSET(defs::xy, x), H5::PredType::NATIVE_INT);
+        type.insertMember("y", HOFFSET(defs::xy, y), H5::PredType::NATIVE_INT);
+        // read
+        defs::xy out{};
+        ds.read(&out, type);
+        return out;
+    }
+};
+
+inline hsize_t get_1d_size(const H5::DataSet &ds) {
+    H5::DataSpace space = ds.getSpace();
+    hsize_t dims[1];
+    space.getSimpleExtentDims(dims);
+    return dims[0];
+}
+
+template <> struct Reader<H5Context, std::vector<defs::ROI>> {
+    static std::vector<defs::ROI> read(const H5Context &ctx,
+                                       const std::string &name) {
+        // define type
+        H5::CompType type(sizeof(defs::ROI));
+        type.insertMember("xmin", HOFFSET(defs::ROI, xmin),
+                          H5::PredType::NATIVE_INT);
+        type.insertMember("xmax", HOFFSET(defs::ROI, xmax),
+                          H5::PredType::NATIVE_INT);
+        type.insertMember("ymin", HOFFSET(defs::ROI, ymin),
+                          H5::PredType::NATIVE_INT);
+        type.insertMember("ymax", HOFFSET(defs::ROI, ymax),
+                          H5::PredType::NATIVE_INT);
+        // read
+        auto ds = ctx.file.openDataSet(HDF5_GROUP + name);
+        auto len = get_1d_size(ds);
+        std::vector<defs::ROI> out{};
+        out.resize(len);
+        ds.read(out.data(), type);
+        return out;
+    }
+};
+
+template <> struct Reader<H5Context, defs::scanParameters> {
+    static defs::scanParameters read(const H5Context &ctx,
+                                     const std::string &name) {
+        // define type
+        H5::CompType type(sizeof(defs::scanParameters));
+        type.insertMember("enable", HOFFSET(defs::scanParameters, enable),
+                          H5::PredType::NATIVE_INT);
+        type.insertMember("dacInd", HOFFSET(defs::scanParameters, dacInd),
+                          H5::PredType::NATIVE_INT);
+        type.insertMember("startOffset",
+                          HOFFSET(defs::scanParameters, startOffset),
+                          H5::PredType::NATIVE_INT);
+        type.insertMember("stopOffset",
+                          HOFFSET(defs::scanParameters, stopOffset),
+                          H5::PredType::NATIVE_INT);
+        type.insertMember("stepSize", HOFFSET(defs::scanParameters, stepSize),
+                          H5::PredType::NATIVE_INT);
+        type.insertMember("dacSettleTime_ns",
+                          HOFFSET(defs::scanParameters, dacSettleTime_ns),
+                          H5::PredType::STD_I64LE);
+        // read
+        auto ds = ctx.file.openDataSet(HDF5_GROUP + name);
+        defs::scanParameters out{};
+        ds.read(&out, type);
+        return out;
+    }
+};
+
+/** arrays/vectors/maps */
+template <> struct Reader<H5Context, std::array<int, 3UL>> {
+    static std::array<int, 3UL> read(const H5Context &ctx,
+                                     const std::string &name) {
+        auto ds = ctx.file.openDataSet(HDF5_GROUP + name);
+        auto len = get_1d_size(ds);
+        check_size(len, 3, name, "HDF5");
+        std::array<int, 3UL> out{};
+        ds.read(out.data(), H5::PredType::NATIVE_INT);
+        return out;
+    }
+};
+
+template <> struct Reader<H5Context, std::array<ns, 3UL>> {
+    static std::array<ns, 3UL> read(const H5Context &ctx,
+                                    const std::string &name) {
+        auto ds = ctx.file.openDataSet(HDF5_GROUP + name);
+        auto len = get_1d_size(ds);
+        check_size(len, 3, name, "HDF5");
+
+        // read int raw char buffer
+        std::vector<const char *> raw(len);
+        ds.read(raw.data(), ds.getStrType());
+
+        std::array<ns, 3UL> out{};
+        for (size_t i = 0; i != len; ++i) {
+            out[i] = StringTo<ns>(raw[i]);
+        }
+        return out;
+    }
+};
+
+template <> struct Reader<H5Context, std::vector<int64_t>> {
+    static std::vector<int64_t> read(const H5Context &ctx,
+                                     const std::string &name) {
+        auto ds = ctx.file.openDataSet(HDF5_GROUP + name);
+        auto len = get_1d_size(ds);
+        std::vector<int64_t> out{};
+        out.resize(len);
+        ds.read(out.data(), H5::PredType::STD_I64LE);
+        return out;
+    }
+};
+
+template <> struct Reader<H5Context, std::map<std::string, std::string>> {
+    static std::map<std::string, std::string> read(const H5Context &ctx,
+                                                   const std::string &name) {
+        std::map<std::string, std::string> out{};
+        // dim
+        auto ds = ctx.file.openDataSet(HDF5_GROUP + name);
+        auto len = get_1d_size(ds);
+        // empty ds
+        if (len == 0) {
+            return out;
+        }
+        // define type
+        auto strType = ds.getStrType();
+        H5::CompType mapType(sizeof(char *) * 2);
+        mapType.insertMember("key", 0, strType);
+        mapType.insertMember("value", sizeof(char *), strType);
+        struct KeyValue {
+            const char *key;
+            const char *value;
+        };
+        // read
+        std::vector<KeyValue> kv_vector(len);
+        ds.read(kv_vector.data(), mapType);
+        for (const auto &kv : kv_vector) {
+            out[kv.key] = kv.value;
+        }
+        return out;
+    }
+};
+
+} // namespace sls::test::master_file
+
+#endif
\ No newline at end of file
diff --git a/slsDetectorSoftware/tests/master_file/ReadersJson.cpp b/slsDetectorSoftware/tests/master_file/ReadersJson.cpp
deleted file mode 100644
index 5fb2c7584..000000000
--- a/slsDetectorSoftware/tests/master_file/ReadersJson.cpp
+++ /dev/null
@@ -1,57 +0,0 @@
-// SPDX-License-Identifier: LGPL-3.0-or-other
-// Copyright (C) 2021 Contributors to the SLS Detector Package
-
-#include "Readers.h"
-
-namespace sls::test::master_file {
-
-/* --scalar reads-- */
-template <>
-struct Reader<JsonContext, int> {
-    static int read(const JsonContext &ctx, const std::string &name) {
-        return ctx.doc[name.c_str()].GetInt();
-    }
-};
-
-template<>
-struct Reader<JsonContext, uint32_t> {
-
-    static uint32_t read(const JsonContext& ctx,
-                         const std::string& name) {
-
-        return ctx.doc[name.c_str()].GetUint();
-
-    }
-};
-
-template<>
-struct Reader<JsonContext, uint64_t> {
-
-    static uint64_t read(const JsonContext& ctx,
-                         const std::string& name) {
-
-        return ctx.doc[name.c_str()].GetUint64();
-    }
-};
-
-template<>
-struct Reader<JsonContext, double> {
-
-    static double read(const JsonContext& ctx,
-                       const std::string& name) {
-
-        return ctx.doc[name.c_str()].GetDouble();
-    }
-};
-
-template<>
-struct Reader<JsonContext, std::string> {
-
-    static std::string read(const JsonContext& ctx,
-                            const std::string& name) {
-
-        return ctx.doc[name.c_str()].GetString();
-    }
-};
-
-} // namespace sls::test::master_file
\ No newline at end of file
diff --git a/slsDetectorSoftware/tests/master_file/ReadersJson.h b/slsDetectorSoftware/tests/master_file/ReadersJson.h
new file mode 100644
index 000000000..924c04bd9
--- /dev/null
+++ b/slsDetectorSoftware/tests/master_file/ReadersJson.h
@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: LGPL-3.0-or-other
+// Copyright (C) 2021 Contributors to the SLS Detector Package
+#pragma once
+
+#include "Readers.h"
+#include "sls/ToString.h"
+#include "sls/sls_detector_defs.h"
+
+#include <rapidjson/document.h>
+
+namespace sls::test::master_file {
+using ns = std::chrono::nanoseconds;
+
+/* --scalar reads-- */
+template <> struct Reader<JsonContext, int> {
+    static int read(const JsonContext &ctx, const std::string &name) {
+        return ctx.doc[name.c_str()].GetInt();
+    }
+};
+
+template <> struct Reader<JsonContext, uint32_t> {
+    static uint32_t read(const JsonContext &ctx, const std::string &name) {
+        return ctx.doc[name.c_str()].GetUint();
+    }
+};
+
+template <> struct Reader<JsonContext, uint64_t> {
+    static uint64_t read(const JsonContext &ctx, const std::string &name) {
+        return ctx.doc[name.c_str()].GetUint64();
+    }
+};
+
+template <> struct Reader<JsonContext, double> {
+    static double read(const JsonContext &ctx, const std::string &name) {
+        return ctx.doc[name.c_str()].GetDouble();
+    }
+};
+
+template <> struct Reader<JsonContext, std::string> {
+    static std::string read(const JsonContext &ctx, const std::string &name) {
+        return ctx.doc[name.c_str()].GetString();
+    }
+};
+
+/** complex types */
+template <> struct Reader<JsonContext, defs::xy> {
+    static defs::xy read(const JsonContext &ctx, const std::string &name) {
+        defs::xy out{};
+        out.x = ctx.doc[name.c_str()]["x"].GetInt();
+        out.y = ctx.doc[name.c_str()]["y"].GetInt();
+        return out;
+    }
+};
+
+template <> struct Reader<JsonContext, std::vector<defs::ROI>> {
+    static std::vector<defs::ROI> read(const JsonContext &ctx,
+                                       const std::string &name) {
+        std::vector<defs::ROI> out{};
+        for (const auto &item : ctx.doc[name.c_str()].GetArray()) {
+            defs::ROI r{};
+            r.xmin = item["xmin"].GetInt();
+            r.xmax = item["xmax"].GetInt();
+            r.ymin = item["ymin"].GetInt();
+            r.ymax = item["ymax"].GetInt();
+            out.push_back(r);
+        }
+        return out;
+    }
+};
+
+template <> struct Reader<JsonContext, defs::scanParameters> {
+    static defs::scanParameters read(const JsonContext &ctx,
+                                     const std::string &name) {
+        defs::scanParameters out{};
+        const auto &s = ctx.doc[name.c_str()].GetObject();
+        out.enable = s["enable"].GetInt();
+        out.dacInd = static_cast<defs::dacIndex>(s["dacInd"].GetInt());
+        out.startOffset = s["start offset"].GetInt();
+        out.stopOffset = s["stop offset"].GetInt();
+        out.stepSize = s["step size"].GetInt();
+        out.dacSettleTime_ns = s["dac settle time ns"].GetInt64();
+        return out;
+    }
+};
+
+/** arrays/vectors/maps */
+template <> struct Reader<JsonContext, std::array<int, 3UL>> {
+    static std::array<int, 3UL> read(const JsonContext &ctx,
+                                     const std::string &name) {
+        const auto &arr = ctx.doc[name.c_str()].GetArray();
+        check_size(arr.Size(), 3, name, "JSON");
+
+        std::array<int, 3UL> out{};
+        for (size_t i = 0; i < 3; ++i) {
+            out[i] = arr[i].GetInt();
+        }
+        return out;
+    }
+};
+
+template <> struct Reader<JsonContext, std::array<ns, 3UL>> {
+    static std::array<ns, 3UL> read(const JsonContext &ctx,
+                                    const std::string &name) {
+        const auto &arr = ctx.doc[name.c_str()].GetArray();
+        check_size(arr.Size(), 3, name, "JSON");
+
+        std::array<ns, 3UL> out{};
+        for (size_t i = 0; i < 3; ++i) {
+            std::string sval = arr[i].GetString();
+            out[i] = StringTo<ns>(sval);
+        }
+        return out;
+    }
+};
+
+template <> struct Reader<JsonContext, std::vector<int64_t>> {
+    static std::vector<int64_t> read(const JsonContext &ctx,
+                                     const std::string &name) {
+        std::vector<int64_t> out{};
+        for (const auto &item : ctx.doc[name.c_str()].GetArray()) {
+            out.push_back(item.GetInt64());
+        }
+        return out;
+    }
+};
+
+template <> struct Reader<JsonContext, std::map<std::string, std::string>> {
+    static std::map<std::string, std::string> read(const JsonContext &ctx,
+                                                   const std::string &name) {
+        std::map<std::string, std::string> out{};
+        for (const auto &m : ctx.doc[name.c_str()].GetObject()) {
+            out[m.name.GetString()] = m.value.GetString();
+        }
+        return out;
+    }
+};
+
+} // namespace sls::test::master_file
\ No newline at end of file