feat: Add Plc.ReadStatusAsync

S7.Net/PLCHelpers.cs

@@ -329,5 +329,15 @@ namespace S7.Net
 
             return package.ToArray();
         }
+
+        private static byte[] BuildSzlReadRequestPackage(ushort szlId, ushort szlIndex)
+        {
+            var stream = new System.IO.MemoryStream();
+            
+            WriteSzlReadRequest(stream, szlId, szlIndex);
+            stream.SetLength(stream.Position);
+
+            return stream.ToArray();
+        }
     }
 }

S7.Net/PlcAsynchronous.cs

@@ -312,6 +312,17 @@ namespace S7.Net
             return dataItems;
         }
 
+        /// <summary>
+        /// Read the current status from the PLC. A value of 0x08 indicates the PLC is in run status, regardless of the PLC type.
+        /// </summary>
+        /// <returns>A task that represents the asynchronous operation, with it's result set to the current PLC status on completion.</returns>
+        public async Task<byte> ReadStatusAsync(CancellationToken cancellationToken) {
+            var dataToSend = BuildSzlReadRequestPackage(0x0424, 0);
+            var s7data = await RequestTsduAsync(dataToSend, cancellationToken);
+
+            return (byte) (s7data[94] & 0x0f);
+        }
+
         /// <summary>
         /// Write a number of bytes from a DB starting from a specified index. This handles more than 200 bytes with multiple requests.
         /// If the write was not successful, check LastErrorCode or LastErrorString.