diff --git a/Cargo.lock b/Cargo.lock
index 1040625..ae584a1 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -78,6 +78,12 @@ version = "0.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0cc23270f6e1808e30a928bdc84dea0b9b4136a8bc82338574f23baf47bbd280"
 
+[[package]]
+name = "hex"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7f24254aa9a54b5c858eaee2f5bccdb46aaf0e486a595ed5fd8f86ba55232a70"
+
 [[package]]
 name = "ipnetwork"
 version = "0.20.0"
@@ -87,6 +93,12 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "itoa"
+version = "1.0.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7ee5b5339afb4c41626dde77b7a611bd4f2c202b897852b4bcf5d03eddc61010"
+
 [[package]]
 name = "libc"
 version = "0.2.178"
@@ -129,10 +141,13 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "bytes",
+ "hex",
  "pcap",
  "pnet",
  "sawp",
  "sawp-modbus",
+ "serde",
+ "serde_json",
 ]
 
 [[package]]
@@ -341,6 +356,12 @@ version = "0.8.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7a2d987857b319362043e95f5353c0535c1f58eec5336fdfcf626430af7def58"
 
+[[package]]
+name = "ryu"
+version = "1.0.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "62049b2877bf12821e8f9ad256ee38fdc31db7387ec2d3b3f403024de2034aea"
+
 [[package]]
 name = "sawp"
 version = "0.13.1"
@@ -390,6 +411,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9a8e94ea7f378bd32cbbd37198a4a91436180c5bb472411e48b5ec2e2124ae9e"
 dependencies = [
  "serde_core",
+ "serde_derive",
 ]
 
 [[package]]
@@ -412,6 +434,19 @@ dependencies = [
  "syn 2.0.111",
 ]
 
+[[package]]
+name = "serde_json"
+version = "1.0.145"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "402a6f66d8c709116cf22f558eab210f5a50187f702eb4d7e5ef38d9a7f1c79c"
+dependencies = [
+ "itoa",
+ "memchr",
+ "ryu",
+ "serde",
+ "serde_core",
+]
+
 [[package]]
 name = "shlex"
 version = "1.3.0"
diff --git a/network/Cargo.toml b/network/Cargo.toml
index d919f41..1301a27 100644
--- a/network/Cargo.toml
+++ b/network/Cargo.toml
@@ -12,3 +12,6 @@ pnet = "0.35.0"
 
 anyhow = "1.0.100"
 bytes = "1.11.0"
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+hex = "0.4"
diff --git a/network/src/types/modbus.rs b/network/src/types/modbus.rs
index 43ca1ac..677c1d6 100644
--- a/network/src/types/modbus.rs
+++ b/network/src/types/modbus.rs
@@ -1,45 +1,101 @@
 use anyhow::{Context, Error, Result, anyhow, bail};
-use bytes::Bytes;
+use bytes::{Bytes, BytesMut};
 use sawp::error::Error as SawpError;
 use sawp::error::ErrorKind;
 use sawp::parser::{Direction, Parse};
-use sawp_modbus::{Message, Modbus};
+use sawp_modbus::{Data, Message, Modbus};
+use serde::Deserialize;
+use serde_json::{Value, json};
+use std::convert::TryInto;
 
 use pcap::Capture;
 use pcap::Offline;
 use pnet::packet::Packet;
 use pnet::packet::ethernet::{EtherTypes, EthernetPacket};
+use pnet::packet::ip::IpNextHeaderProtocols;
 use pnet::packet::ipv4::Ipv4Packet;
 use pnet::packet::ipv6::Ipv6Packet;
 use pnet::packet::tcp::TcpPacket;
 use std::collections::{HashMap, HashSet};
 
-fn parse_bytes(input: &[u8]) -> Result<&[u8]> {
+#[derive(Debug, Deserialize)]
+pub struct Config {
+    pub functions: Vec<FunctionDescriptor>,
+}
+
+#[derive(Debug, Deserialize)]
+pub struct FunctionDescriptor {
+    pub function_code: u8,
+    pub name: Option<String>,
+    pub request: Option<Vec<FieldDescriptor>>,
+    pub response: Option<Vec<FieldDescriptor>>,
+}
+
+#[derive(Debug, Deserialize)]
+pub struct FieldDescriptor {
+    pub name: String,
+    #[serde(rename = "type")]
+    pub ty: FieldType,
+    #[serde(default)]
+    pub length: Option<usize>,
+    #[serde(default)]
+    pub length_from: Option<String>,
+    #[serde(default)]
+    pub scale: Option<f64>,
+    #[serde(default)]
+    pub enum_map: Option<HashMap<u64, String>>,
+}
+
+#[derive(Debug, Deserialize)]
+#[serde(rename_all = "lowercase")]
+pub enum FieldType {
+    U8,
+    U16,
+    U32,
+    I16,
+    Bytes,
+    Rest,
+}
+
+// Build lookup map
+type FuncMap = HashMap<u8, FunctionDescriptor>;
+
+fn parse_bytes_zero_copy(mut buf: BytesMut) -> Result<BytesMut> {
     let modbus = Modbus::default();
-    let mut bytes = input;
-    while bytes.len() > 0 {
-        // If we know that this is a request or response, change the Direction
-        // for a more accurate parsing
-        match modbus.parse(bytes, Direction::Unknown) {
-            // The parser succeeded and returned the remaining bytes and the parsed modbus message
+
+    while !buf.is_empty() {
+        match modbus.parse(buf.as_ref(), Direction::Unknown) {
             Ok((rest, Some(message))) => {
                 println!("Modbus message: {:?}", message);
-                bytes = rest;
+                // rest is a subslice of buf.as_ref(); compute how many bytes consumed
+                let consumed = unsafe {
+                    // pointer difference: rest.as_ptr() - buf.as_ptr()
+                    rest.as_ptr().offset_from(buf.as_ptr()) as usize
+                };
+                // consume the prefix up to consumed
+                let _ = buf.split_to(consumed);
+                // continue with the remainder in buf (zero-copy)
+            }
+            Ok((rest, None)) => {
+                // parser needs more bytes; return remaining buffer as-is
+                // We want to keep the exact remaining bytes (rest points into buf)
+                // Compute offset of rest and split off the prefix, returning the suffix.
+                let offset = unsafe { rest.as_ptr().offset_from(buf.as_ptr()) as usize };
+                // split off prefix, keep suffix in `suffix`
+                let _prefix = buf.split_to(offset);
+                return Ok(buf);
             }
-            // The parser recognized that this might be modbus and made some progress,
-            // but more bytes are needed
-            Ok((rest, None)) => return Ok(rest),
-            // The parser was unable to determine whether this was modbus or not and more
-            // bytes are needed
             Err(SawpError {
                 kind: ErrorKind::Incomplete(_),
-            }) => return Ok(bytes),
-            // The parser determined that this was not modbus
+            }) => {
+                // need more bytes; return current buffer unchanged
+                return Ok(buf);
+            }
             Err(e) => return Err(anyhow::Error::new(e)).context("failed to parse modbus"),
         }
     }
 
-    Ok(bytes)
+    Ok(buf)
 }
 
 fn get_tcp_data_v4(buf: Bytes) -> Result<Bytes> {
@@ -67,3 +123,254 @@ fn get_tcp_data_v6(buf: Bytes) -> Result<Bytes> {
             ..(tcp_payload.as_ptr() as usize - buf.as_ptr() as usize + tcp_payload.len()),
     ))
 }
+
+pub fn get_tcp_payload_from_eth(eth: &EthernetPacket) -> Result<Bytes> {
+    let pkt = eth.packet(); // returns &[u8]
+    match eth.get_ethertype() {
+        EtherTypes::Ipv4 => {
+            let ipv4 = Ipv4Packet::new(pkt).ok_or_else(|| anyhow!("failed to parse ipv4"))?;
+            if ipv4.get_next_level_protocol() != IpNextHeaderProtocols::Tcp {
+                return Err(anyhow!("not a TCP packet"));
+            }
+            let ipv4_payload = ipv4.payload();
+            let tcp = TcpPacket::new(ipv4_payload).ok_or_else(|| anyhow!("failed to parse tcp"))?;
+            let tcp_payload = tcp.payload();
+
+            // compute byte offsets relative to the original packet slice
+            let base = pkt.as_ptr() as usize;
+            let start = tcp_payload.as_ptr() as usize - base;
+            let end = start + tcp_payload.len();
+            Ok(Bytes::copy_from_slice(&pkt[start..end]).slice(0..tcp_payload.len()))
+        }
+
+        EtherTypes::Ipv6 => {
+            let ipv6 = Ipv6Packet::new(pkt).ok_or_else(|| anyhow!("failed to parse ipv6"))?;
+            if ipv6.get_next_header() != IpNextHeaderProtocols::Tcp {
+                return Err(anyhow!("not a TCP packet"));
+            }
+            let ipv6_payload = ipv6.payload();
+            let tcp = TcpPacket::new(ipv6_payload).ok_or_else(|| anyhow!("failed to parse tcp"))?;
+            let tcp_payload = tcp.payload();
+
+            let base = pkt.as_ptr() as usize;
+            let start = tcp_payload.as_ptr() as usize - base;
+            let end = start + tcp_payload.len();
+            Ok(Bytes::copy_from_slice(&pkt[start..end]).slice(0..tcp_payload.len()))
+        }
+
+        _ => Err(anyhow!("not IPv4/IPv6")),
+    }
+}
+
+/// Top-level parse entry: takes sawp_modbus::Message and descriptor map.
+/// Returns JSON object with parsed fields.
+pub fn parse_sawp_message(
+    msg: &Message,
+    map: &FuncMap,
+    is_response: bool,
+) -> Result<Value, String> {
+    // obtain function code and exception flag from msg.function
+    let mut fn_code = msg.function.raw;
+    let is_exception_fn = (fn_code & 0x80) != 0;
+    if is_exception_fn {
+        fn_code &= 0x7F;
+    }
+
+    // Extract a byte-slice to feed generic PDU parser.
+    // Different Data variants carry bytes differently.
+    let pdu_bytes = match &msg.data {
+        Data::Exception(exc) => {
+            // Exception contains an exception code byte or similar; convert to vec
+            // If Exception type exposes code() or .0, adapt accordingly.
+            // Here we try to obtain a single byte; if Exception is an enum with u8 inside:
+            let code_byte = exc.raw; // if Exception(pub u8)
+            vec![code_byte]
+        }
+        Data::Diagnostic { data, .. } => data.clone(),
+        Data::MEI { data, .. } => data.clone(),
+        Data::Read(read) => {
+            // If Read provides a bytes() method or inner Vec<u8>, extract it.
+            // Adjust depending on actual Read struct — common shape: Read { byte_count, data: Vec<u8> }
+            // Try common fields:
+            if let Some(bytes) = try_extract_read_bytes(read) {
+                bytes
+            } else {
+                return Err("unsupported Read variant layout; adapt extraction".into());
+            }
+        }
+        Data::Write(write) => {
+            if let Some(bytes) = try_extract_write_bytes(write) {
+                bytes
+            } else {
+                return Err("unsupported Write variant layout; adapt extraction".into());
+            }
+        }
+        Data::ReadWrite { read, write } => {
+            // For ReadWrite, decide which side to parse based on is_response.
+            // If is_response==true, prefer read bytes; else use write bytes.
+            if is_response {
+                if let Some(bytes) = try_extract_read_bytes(read) {
+                    bytes
+                } else {
+                    return Err("unsupported Read variant in ReadWrite".into());
+                }
+            } else {
+                if let Some(bytes) = try_extract_write_bytes(write) {
+                    bytes
+                } else {
+                    return Err("unsupported Write variant in ReadWrite".into());
+                }
+            }
+        }
+        Data::ByteVec(v) => v.clone(),
+        Data::Empty => vec![],
+    };
+
+    // If exception function: treat as exception
+    if is_exception_fn {
+        if pdu_bytes.is_empty() {
+            return Err("exception message missing exception code".into());
+        }
+        return Ok(json!({
+            "unit": msg.unit_id,
+            "function": msg.function.raw,
+            "exception": pdu_bytes[0],
+        }));
+    }
+
+    // Lookup descriptor and parse using generic byte-slice parser
+    let desc = map
+        .get(&fn_code)
+        .ok_or_else(|| format!("unknown function code: {}", fn_code))?;
+    let fields = if is_response {
+        desc.response.as_ref()
+    } else {
+        desc.request.as_ref()
+    }
+    .ok_or_else(|| "no descriptor for chosen direction".to_string())?;
+
+    parse_with_descriptor(&pdu_bytes, msg.unit_id, msg.function.raw, fields)
+}
+
+/// Generic parser: parse bytes per FieldDescriptor sequence.
+fn parse_with_descriptor(
+    pdu: &[u8],
+    unit: u8,
+    function: u8,
+    fields: &Vec<FieldDescriptor>,
+) -> Result<Value, String> {
+    let mut cursor = 0usize;
+    let mut out = serde_json::Map::new();
+
+    for fd in fields {
+        match fd.ty {
+            FieldType::U8 => {
+                if cursor + 1 > pdu.len() {
+                    return Err(format!("field {} out of bounds", fd.name));
+                }
+                let v = pdu[cursor] as u64;
+                cursor += 1;
+                insert_mapped(&mut out, fd, v)?;
+            }
+            FieldType::U16 => {
+                if cursor + 2 > pdu.len() {
+                    return Err(format!("field {} out of bounds", fd.name));
+                }
+                let be = &pdu[cursor..cursor + 2];
+                let v = u16::from_be_bytes(be.try_into().unwrap()) as u64;
+                cursor += 2;
+                insert_mapped(&mut out, fd, v)?;
+            }
+            FieldType::U32 => {
+                if cursor + 4 > pdu.len() {
+                    return Err(format!("field {} out of bounds", fd.name));
+                }
+                let be = &pdu[cursor..cursor + 4];
+                let v = u32::from_be_bytes(be.try_into().unwrap()) as u64;
+                cursor += 4;
+                insert_mapped(&mut out, fd, v)?;
+            }
+            FieldType::I16 => {
+                if cursor + 2 > pdu.len() {
+                    return Err(format!("field {} out of bounds", fd.name));
+                }
+                let be = &pdu[cursor..cursor + 2];
+                let v = i16::from_be_bytes(be.try_into().unwrap()) as i64;
+                cursor += 2;
+                if let Some(scale) = fd.scale {
+                    out.insert(fd.name.clone(), json!((v as f64) * scale));
+                } else {
+                    out.insert(fd.name.clone(), json!(v));
+                }
+            }
+            FieldType::Bytes => {
+                let len = if let Some(ref lf) = fd.length_from {
+                    let ref_val = out
+                        .get(lf)
+                        .ok_or_else(|| format!("length_from {} not parsed yet", lf))?;
+                    let n = ref_val
+                        .as_u64()
+                        .ok_or_else(|| format!("length_from {} not integer", lf))?
+                        as usize;
+                    n
+                } else if let Some(l) = fd.length {
+                    l
+                } else {
+                    return Err(format!("bytes field {} missing length", fd.name));
+                };
+                if cursor + len > pdu.len() {
+                    return Err(format!("field {} out of bounds", fd.name));
+                }
+                let slice = &pdu[cursor..cursor + len];
+                cursor += len;
+                out.insert(fd.name.clone(), json!(hex::encode(slice)));
+            }
+            FieldType::Rest => {
+                let slice = &pdu[cursor..];
+                cursor = pdu.len();
+                out.insert(fd.name.clone(), json!(hex::encode(slice)));
+            }
+        }
+    }
+
+    if cursor != pdu.len() {
+        out.insert("_trailing".to_string(), json!(hex::encode(&pdu[cursor..])));
+    }
+
+    let mut root = serde_json::Map::new();
+    root.insert("unit".to_string(), json!(unit));
+    root.insert("function".to_string(), json!(function));
+    root.insert("fields".to_string(), Value::Object(out));
+    Ok(Value::Object(root))
+}
+
+fn insert_mapped(
+    map: &mut serde_json::Map<String, Value>,
+    fd: &FieldDescriptor,
+    raw: u64,
+) -> Result<(), String> {
+    if let Some(ref enum_map) = fd.enum_map {
+        if let Some(name) = enum_map.get(&raw) {
+            map.insert(fd.name.clone(), json!(name));
+            return Ok(());
+        }
+    }
+    if let Some(scale) = fd.scale {
+        map.insert(fd.name.clone(), json!((raw as f64) * scale));
+    } else {
+        map.insert(fd.name.clone(), json!(raw));
+    }
+    Ok(())
+}
+
+/// Helper extraction functions: adapt these to the real Read/Write structs in your sawp_modbus version.
+/// These try common shapes; replace with direct field access if necessary.
+fn try_extract_read_bytes<T>(_read: &T) -> Option<Vec<u8>> {
+    // Replace with actual extraction, for example:
+    // Some(read.data.clone()) or Some(read.bytes.clone())
+    None
+}
+fn try_extract_write_bytes<T>(_write: &T) -> Option<Vec<u8>> {
+    // Replace with actual extraction
+    None
+}