diff --git a/S7.Net/Types/DateTime.cs b/S7.Net/Types/DateTime.cs new file mode 100644 index 0000000..8dc7582 --- /dev/null +++ b/S7.Net/Types/DateTime.cs @@ -0,0 +1,111 @@ +using System; + +namespace S7.Net.Types +{ + /// + /// Contains the methods to convert between and S7 representation of datetime values. + /// + public static class DateTime + { + /// + /// The minimum value supported by the specification. + /// + public static readonly System.DateTime SpecMinimumDateTime = new System.DateTime(1990, 1, 1); + + /// + /// The maximum value supported by the specification. + /// + public static readonly System.DateTime SpecMaximumDateTime = new System.DateTime(2089, 12, 31, 23, 59, 59, 999); + + /// + /// Parses a value from bytes. + /// + /// Input bytes read from PLC. + /// A object representing the value read from PLC. + /// Thrown when the length of + /// is not 8 or any value in + /// is outside the valid range of values. + public static System.DateTime FromByteArray(byte[] bytes) + { + if (bytes.Length != 8) + throw new ArgumentOutOfRangeException(nameof(bytes), bytes.Length, + $"Parsing a DateTime requires exactly 8 bytes of input data, input data is {bytes.Length} bytes long."); + + int DecodeBcd(byte input) => 10 * (input >> 4) + (input & 0b00001111); + + int ByteToYear(byte bcdYear) + { + var input = DecodeBcd(bcdYear); + if (input < 90) return input + 2000; + if (input < 100) return input + 1900; + + throw new ArgumentOutOfRangeException(nameof(bcdYear), bcdYear, + $"Value '{input}' is higher than the maximum '99' of S7 date and time representation."); + } + + int AssertRangeInclusive(int input, byte min, byte max, string field) + { + if (input < min) + throw new ArgumentOutOfRangeException(nameof(input), input, + $"Value '{input}' is lower than the minimum '{min}' allowed for {field}."); + if (input > max) + throw new ArgumentOutOfRangeException(nameof(input), input, + $"Value '{input}' is higher than the maximum '{max}' allowed for {field}."); + + return input; + } + + var year = ByteToYear(bytes[0]); + var month = AssertRangeInclusive(DecodeBcd(bytes[1]), 1, 12, "month"); + var day = AssertRangeInclusive(DecodeBcd(bytes[2]), 1, 31, "day of month"); + var hour = AssertRangeInclusive(DecodeBcd(bytes[3]), 0, 23, "hour"); + var minute = AssertRangeInclusive(DecodeBcd(bytes[4]), 0, 59, "minute"); + var second = AssertRangeInclusive(DecodeBcd(bytes[5]), 0, 59, "second"); + var hsec = AssertRangeInclusive(DecodeBcd(bytes[6]), 0, 99, "first two millisecond digits"); + var msec = AssertRangeInclusive(bytes[7] >> 4, 0, 9, "third millisecond digit"); + var dayOfWeek = AssertRangeInclusive(bytes[7] & 0b00001111, 1, 7, "day of week"); + + return new System.DateTime(year, month, day, hour, minute, second, hsec * 10 + msec); + } + + /// + /// Converts a value to a byte array. + /// + /// The DateTime value to convert. + /// A byte array containing the S7 date time representation of . + /// Thrown when the value of + /// is before + /// or after . + public static byte[] ToByteArray(System.DateTime dateTime) + { + byte EncodeBcd(int value) + { + return (byte) ((value / 10 << 4) | value % 10); + } + + if (dateTime < SpecMinimumDateTime) + throw new ArgumentOutOfRangeException(nameof(dateTime), dateTime, + $"Date time '{dateTime}' is before the minimum '{SpecMinimumDateTime}' supported in S7 date time representation."); + + if (dateTime > SpecMaximumDateTime) + throw new ArgumentOutOfRangeException(nameof(dateTime), dateTime, + $"Date time '{dateTime}' is after the maximum '{SpecMaximumDateTime}' supported in S7 date time representation."); + + byte MapYear(int year) => (byte) (year < 2000 ? year - 1900 : year - 2000); + + int DayOfWeekToInt(DayOfWeek dayOfWeek) => (int) dayOfWeek + 1; + + return new[] + { + EncodeBcd(MapYear(dateTime.Year)), + EncodeBcd(dateTime.Month), + EncodeBcd(dateTime.Day), + EncodeBcd(dateTime.Hour), + EncodeBcd(dateTime.Minute), + EncodeBcd(dateTime.Second), + EncodeBcd(dateTime.Millisecond / 10), + (byte) (dateTime.Millisecond % 10 << 4 | DayOfWeekToInt(dateTime.DayOfWeek)) + }; + } + } +} \ No newline at end of file