diff --git a/vendors/elsys/codecs/elsys.js b/vendors/elsys/codecs/elsys.js
new file mode 100644
index 0000000..614810d
--- /dev/null
+++ b/vendors/elsys/codecs/elsys.js
@@ -0,0 +1,211 @@
+/*
+  ELSYS payload decoder for ChirpStack v4.
+  Based on the official Elsys payload decoder.
+  www.elsys.se
+  peter@elsys.se
+
+  Adapted for chirpstack-device-profiles decodeUplink/encodeDownlink format.
+*/
+
+var TYPE_TEMP         = 0x01; // temp 2 bytes -3276.8°C to 3276.7°C
+var TYPE_RH           = 0x02; // Humidity 1 byte 0-100%
+var TYPE_ACC          = 0x03; // Acceleration 3 bytes X,Y,Z -128 to 127 +/-63=1G
+var TYPE_LIGHT        = 0x04; // Light 2 bytes 0-65535 Lux
+var TYPE_MOTION       = 0x05; // No of motion 1 byte 0-255
+var TYPE_CO2          = 0x06; // CO2 2 bytes 0-65535 ppm
+var TYPE_VDD          = 0x07; // Battery mV 2 bytes 0-65535
+var TYPE_ANALOG1      = 0x08; // Analog input 1 2 bytes 0-65535 mV
+var TYPE_GPS          = 0x09; // GPS 6 bytes lat(3),long(3)
+var TYPE_PULSE1       = 0x0A; // Pulse input 1 relative 2 bytes
+var TYPE_PULSE1_ABS   = 0x0B; // Pulse input 1 absolute 4 bytes
+var TYPE_EXT_TEMP1    = 0x0C; // External temp 1 2 bytes -3276.8°C to 3276.7°C
+var TYPE_EXT_DIGITAL  = 0x0D; // Digital input 1 byte
+var TYPE_EXT_DISTANCE = 0x0E; // Distance sensor 2 bytes 0-65535 mm
+var TYPE_ACC_MOTION   = 0x0F; // Acc motion 1 byte 0-255
+var TYPE_IR_TEMP      = 0x10; // IR temperature 4 bytes internal(2),external(2)
+var TYPE_OCCUPANCY    = 0x11; // Occupancy 1 byte
+var TYPE_WATERLEAK    = 0x12; // Water leak 1 byte 0-255
+var TYPE_GRIDEYE      = 0x13; // Grideye data 65 bytes
+var TYPE_PRESSURE     = 0x14; // Pressure 4 bytes (hPa)
+var TYPE_SOUND        = 0x15; // Sound 2 bytes (peak,avg)
+var TYPE_PULSE2       = 0x16; // Pulse input 2 relative 2 bytes
+var TYPE_PULSE2_ABS   = 0x17; // Pulse input 2 absolute 4 bytes
+var TYPE_ANALOG2      = 0x18; // Analog input 2 2 bytes 0-65535 mV
+var TYPE_EXT_TEMP2    = 0x19; // External temp 2 2 bytes -3276.8°C to 3276.7°C
+var TYPE_EXT_DIGITAL2 = 0x1A; // Digital input 2 1 byte
+var TYPE_EXT_ANALOG_UV= 0x1B; // Analog UV 4 bytes
+
+function bin16dec(bin) {
+    var num = bin & 0xFFFF;
+    if (0x8000 & num)
+        num = -(0x010000 - num);
+    return num;
+}
+
+function bin8dec(bin) {
+    var num = bin & 0xFF;
+    if (0x80 & num)
+        num = -(0x0100 - num);
+    return num;
+}
+
+function DecodeElsysPayload(data) {
+    var obj = {};
+    for (var i = 0; i < data.length; i++) {
+        switch (data[i]) {
+            case TYPE_TEMP:
+                var temp = (data[i + 1] << 8) | (data[i + 2]);
+                temp = bin16dec(temp);
+                obj.temperature = temp / 10;
+                i += 2;
+                break;
+            case TYPE_RH:
+                obj.humidity = data[i + 1];
+                i += 1;
+                break;
+            case TYPE_ACC:
+                obj.x = bin8dec(data[i + 1]);
+                obj.y = bin8dec(data[i + 2]);
+                obj.z = bin8dec(data[i + 3]);
+                i += 3;
+                break;
+            case TYPE_LIGHT:
+                obj.light = (data[i + 1] << 8) | (data[i + 2]);
+                i += 2;
+                break;
+            case TYPE_MOTION:
+                obj.motion = data[i + 1];
+                i += 1;
+                break;
+            case TYPE_CO2:
+                obj.co2 = (data[i + 1] << 8) | (data[i + 2]);
+                i += 2;
+                break;
+            case TYPE_VDD:
+                obj.vdd = (data[i + 1] << 8) | (data[i + 2]);
+                i += 2;
+                break;
+            case TYPE_ANALOG1:
+                obj.analog1 = (data[i + 1] << 8) | (data[i + 2]);
+                i += 2;
+                break;
+            case TYPE_GPS:
+                obj.lat = (data[i + 1] << 16) | (data[i + 2] << 8) | (data[i + 3]);
+                obj.long = (data[i + 4] << 16) | (data[i + 5] << 8) | (data[i + 6]);
+                i += 6;
+                break;
+            case TYPE_PULSE1:
+                obj.pulse1 = (data[i + 1] << 8) | (data[i + 2]);
+                i += 2;
+                break;
+            case TYPE_PULSE1_ABS:
+                obj.pulseAbs = (data[i + 1] << 24) | (data[i + 2] << 16) | (data[i + 3] << 8) | (data[i + 4]);
+                i += 4;
+                break;
+            case TYPE_EXT_TEMP1:
+                var temp = (data[i + 1] << 8) | (data[i + 2]);
+                temp = bin16dec(temp);
+                obj.externalTemperature = temp / 10;
+                i += 2;
+                break;
+            case TYPE_EXT_DIGITAL:
+                obj.digital = data[i + 1];
+                i += 1;
+                break;
+            case TYPE_EXT_DISTANCE:
+                obj.distance = (data[i + 1] << 8) | (data[i + 2]);
+                i += 2;
+                break;
+            case TYPE_ACC_MOTION:
+                obj.accMotion = data[i + 1];
+                i += 1;
+                break;
+            case TYPE_IR_TEMP:
+                var iTemp = (data[i + 1] << 8) | (data[i + 2]);
+                iTemp = bin16dec(iTemp);
+                var eTemp = (data[i + 3] << 8) | (data[i + 4]);
+                eTemp = bin16dec(eTemp);
+                obj.irInternalTemperature = iTemp / 10;
+                obj.irExternalTemperature = eTemp / 10;
+                i += 4;
+                break;
+            case TYPE_OCCUPANCY:
+                obj.occupancy = data[i + 1];
+                i += 1;
+                break;
+            case TYPE_WATERLEAK:
+                obj.waterleak = data[i + 1];
+                i += 1;
+                break;
+            case TYPE_GRIDEYE:
+                var ref = data[i + 1];
+                i++;
+                obj.grideye = [];
+                for (var j = 0; j < 64; j++) {
+                    obj.grideye[j] = ref + (data[1 + i + j] / 10.0);
+                }
+                i += 64;
+                break;
+            case TYPE_PRESSURE:
+                var press = (data[i + 1] << 24) | (data[i + 2] << 16) | (data[i + 3] << 8) | (data[i + 4]);
+                obj.pressure = press / 1000;
+                i += 4;
+                break;
+            case TYPE_SOUND:
+                obj.soundPeak = data[i + 1];
+                obj.soundAvg = data[i + 2];
+                i += 2;
+                break;
+            case TYPE_PULSE2:
+                obj.pulse2 = (data[i + 1] << 8) | (data[i + 2]);
+                i += 2;
+                break;
+            case TYPE_PULSE2_ABS:
+                obj.pulseAbs2 = (data[i + 1] << 24) | (data[i + 2] << 16) | (data[i + 3] << 8) | (data[i + 4]);
+                i += 4;
+                break;
+            case TYPE_ANALOG2:
+                obj.analog2 = (data[i + 1] << 8) | (data[i + 2]);
+                i += 2;
+                break;
+            case TYPE_EXT_TEMP2:
+                var temp = (data[i + 1] << 8) | (data[i + 2]);
+                temp = bin16dec(temp);
+                if (typeof obj.externalTemperature2 === "number") {
+                    obj.externalTemperature2 = [obj.externalTemperature2];
+                }
+                if (typeof obj.externalTemperature2 === "object") {
+                    obj.externalTemperature2.push(temp / 10);
+                } else {
+                    obj.externalTemperature2 = temp / 10;
+                }
+                i += 2;
+                break;
+            case TYPE_EXT_DIGITAL2:
+                obj.digital2 = data[i + 1];
+                i += 1;
+                break;
+            case TYPE_EXT_ANALOG_UV:
+                obj.analogUv = (data[i + 1] << 24) | (data[i + 2] << 16) | (data[i + 3] << 8) | (data[i + 4]);
+                i += 4;
+                break;
+            default:
+                i = data.length;
+                break;
+        }
+    }
+    return obj;
+}
+
+// ChirpStack v4 / LoRa Alliance TS013 codec API
+function decodeUplink(input) {
+    return {
+        data: DecodeElsysPayload(input.bytes),
+    };
+}
+
+function encodeDownlink(input) {
+    return {
+        bytes: [],
+    };
+}
diff --git a/vendors/elsys/codecs/test_decode_elsys.json b/vendors/elsys/codecs/test_decode_elsys.json
new file mode 100644
index 0000000..9ce063e
--- /dev/null
+++ b/vendors/elsys/codecs/test_decode_elsys.json
@@ -0,0 +1,105 @@
+[
+  {
+    "name": "Test decode temperature and humidity",
+    "input": {
+      "fPort": 5,
+      "bytes": [1, 0, 234, 2, 55]
+    },
+    "expected": {
+      "data": {
+        "temperature": 23.4,
+        "humidity": 55
+      }
+    }
+  },
+  {
+    "name": "Test decode temperature, humidity and VDD",
+    "input": {
+      "fPort": 5,
+      "bytes": [1, 0, 198, 2, 42, 7, 14, 10]
+    },
+    "expected": {
+      "data": {
+        "temperature": 19.8,
+        "humidity": 42,
+        "vdd": 3594
+      }
+    }
+  },
+  {
+    "name": "Test decode negative temperature",
+    "input": {
+      "fPort": 5,
+      "bytes": [1, 255, 206, 2, 80]
+    },
+    "expected": {
+      "data": {
+        "temperature": -5.0,
+        "humidity": 80
+      }
+    }
+  },
+  {
+    "name": "Test decode external temperature (DS18B20)",
+    "input": {
+      "fPort": 5,
+      "bytes": [1, 0, 200, 12, 0, 150]
+    },
+    "expected": {
+      "data": {
+        "temperature": 20.0,
+        "externalTemperature": 15.0
+      }
+    }
+  },
+  {
+    "name": "Test decode analog input",
+    "input": {
+      "fPort": 5,
+      "bytes": [1, 0, 180, 8, 19, 136]
+    },
+    "expected": {
+      "data": {
+        "temperature": 18.0,
+        "analog1": 5000
+      }
+    }
+  },
+  {
+    "name": "Test decode pressure",
+    "input": {
+      "fPort": 5,
+      "bytes": [20, 0, 15, 92, 168]
+    },
+    "expected": {
+      "data": {
+        "pressure": 1006.76
+      }
+    }
+  },
+  {
+    "name": "Test decode digital input",
+    "input": {
+      "fPort": 5,
+      "bytes": [1, 0, 210, 13, 1]
+    },
+    "expected": {
+      "data": {
+        "temperature": 21.0,
+        "digital": 1
+      }
+    }
+  },
+  {
+    "name": "Test decode pulse counter",
+    "input": {
+      "fPort": 5,
+      "bytes": [10, 0, 42]
+    },
+    "expected": {
+      "data": {
+        "pulse1": 42
+      }
+    }
+  }
+]
diff --git a/vendors/elsys/codecs/test_encode_elsys.json b/vendors/elsys/codecs/test_encode_elsys.json
new file mode 100644
index 0000000..8e1a761
--- /dev/null
+++ b/vendors/elsys/codecs/test_encode_elsys.json
@@ -0,0 +1,11 @@
+[
+  {
+    "name": "Test encode empty (no downlink encoding supported)",
+    "input": {
+      "data": {}
+    },
+    "expected": {
+      "bytes": []
+    }
+  }
+]
diff --git a/vendors/elsys/devices/elt-2-hp.toml b/vendors/elsys/devices/elt-2-hp.toml
new file mode 100644
index 0000000..a3bbc30
--- /dev/null
+++ b/vendors/elsys/devices/elt-2-hp.toml
@@ -0,0 +1,15 @@
+[device]
+id = "b2c3d4e5-6f7a-8b9c-0d1e-f2a3b4c5d6e7"
+name = "ELT-2 HP"
+description = "Multi-sensor with 2 external sensor inputs. Internal temperature, humidity, accelerometer and barometric pressure. External inputs support analog 0-10V, digital, pulse counter, DS18B20, ultrasonic distance, and water leak sensors. IP67 rated with external antenna."
+
+[[device.firmware]]
+version = "1.0"
+profiles = [
+    "EU868-1_0_3.toml",
+]
+codec = "elsys.js"
+
+[device.metadata]
+product_url = "https://www.elsys.se/shop/product/elt2hp/"
+documentation_url = "https://elsys.se/public/documents/Sensor_payload.pdf"
diff --git a/vendors/elsys/profiles/EU868-1_0_3.toml b/vendors/elsys/profiles/EU868-1_0_3.toml
new file mode 100644
index 0000000..c72c6f0
--- /dev/null
+++ b/vendors/elsys/profiles/EU868-1_0_3.toml
@@ -0,0 +1,25 @@
+[profile]
+id = "c3d4e5f6-7a8b-9c0d-1e2f-a3b4c5d6e7f8"
+vendor_profile_id = 0
+region = "EU868"
+mac_version = "1.0.3"
+reg_params_revision = "A"
+supports_otaa = true
+supports_class_b = false
+supports_class_c = false
+max_eirp = 14
+
+[profile.abp]
+rx1_delay = 0
+rx1_dr_offset = 0
+rx2_dr = 0
+rx2_freq = 0
+
+[profile.class_b]
+timeout_secs = 0
+ping_slot_nb_k = 0
+ping_slot_dr = 0
+ping_slot_freq = 0
+
+[profile.class_c]
+timeout_secs = 0
diff --git a/vendors/elsys/vendor.toml b/vendors/elsys/vendor.toml
new file mode 100644
index 0000000..ed87fe8
--- /dev/null
+++ b/vendors/elsys/vendor.toml
@@ -0,0 +1,10 @@
+[vendor]
+id = "a1b2c3d4-5e6f-7a8b-9c0d-e1f2a3b4c5d6"
+name = "Elsys"
+ouis = ["fc0fee"]
+devices = [
+    "elt-2-hp.toml",
+]
+
+[vendor.metadata]
+homepage = "https://www.elsys.se/"