diff --git a/src/services/serial_service.rs b/src/services/serial_service.rs
index affb9be..79b6e13 100644
--- a/src/services/serial_service.rs
+++ b/src/services/serial_service.rs
@@ -43,8 +43,14 @@ impl SerialService {
 
     pub fn send_command_with_target<T: for<'a> AsRef<str>>(&mut self, command: T, timeout: Option<u64>, target: T) -> Result<bool, String> {
         let target_str = target.as_ref();
-        _ = return match self.send_command(command, timeout) {
-            Ok(resp) => { Ok(resp.contains(target_str)) },
+        return match self.send_command(command, timeout) {
+            Ok(resp) => {
+                if resp.contains(target_str){
+                    return Ok(true);
+                }else{
+                    return Err(resp)
+                }
+            },
             Err(err) => Err(err)
         };
     }
diff --git a/src/services/work_service.rs b/src/services/work_service.rs
index afdf6c0..ededd6e 100644
--- a/src/services/work_service.rs
+++ b/src/services/work_service.rs
@@ -1,3 +1,4 @@
+use crate::models::work_model::WorkModel;
 use crate::services::{serial_service::SerialService, sqlite_service::SqliteService, excel_service::ExcelService};
 
 
@@ -9,10 +10,27 @@ pub struct WorkService {
 
 impl Default for WorkService {
     fn default() -> Self {
-        WorkService {
-            serial_service: *SerialService::new("COM3").unwrap(),
-            sqlite_service: SqliteService::default(),
-            excel_service: ExcelService::new("a").unwrap()
-        }
+        todo!()
+    }
+}
+
+impl WorkService {
+    fn write_imei(&mut self, imei: String) -> Result<bool, String> {
+        let write_imei_command = format!("AT+ECCGSN=\"IMEI\",\"{}\"", imei);
+        return  self.serial_service.send_command_with_target(write_imei_command, None, "OK".to_string());
+    }
+    fn write_sn(&mut self, sn: String) -> Result<bool, String> {
+        let write_sn_command = format!("AT+ECCGSN=\"SN\",\"{}\"", sn);
+        return self.serial_service.send_command_with_target(write_sn_command, None, "OK".to_string());
+    }
+
+    fn check_imei(&mut self, imei: &str) -> Result<bool, String> {
+        let check_imei_command = "AT+CGSN=1".to_string();
+        return self.serial_service.send_command_with_target(check_imei_command, None, imei.to_string());
+    }
+
+    fn check_sn(&mut self, sn: &str) -> Result<bool, String> {
+        let check_sn_command = "AT+CGSN=0".to_string();
+        return self.serial_service.send_command_with_target(check_sn_command, None, sn.to_string());
     }
 }
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