如何在 TwinCAT 3 中将字节数组转换为各种 L'OREAL(double) 值

Question

我现在正试图将我原来的 python 套接字读取代码转换为 TwinCAT3 中的结构文本。 以下是将 read_data = socket.recv(1116) 数据解包成不同事物的原始 python 代码：

def ur_read(read_data):
    moment=[0,0,0,0,0,0]
    joint_p=[0,0,0,0,0,0]
    joint_v=[0,0,0,0,0,0]         
    tcp_p=[0,0,0,0,0,0]
    tcp_v=[0,0,0,0,0,0]
    tcp_force=[0,0,0,0,0,0]
    state=0
    time_new=0
    try:
        for i in range(len(read_data)):            
            if [read_data[i],read_data[i+1],read_data[i+2],read_data[i+3]] == [0,0,4,92]:
                time = struct.unpack('>d', read_data[i+4:i+12])
                moment[0], = struct.unpack('>d', read_data[i+204:i+212])
                moment[1], = struct.unpack('>d', read_data[i+212:i+220])
                moment[2], = struct.unpack('>d', read_data[i+220:i+228])
                moment[3], = struct.unpack('>d', read_data[i+228:i+236])
                moment[4], = struct.unpack('>d', read_data[i+236:i+244])
                moment[5], = struct.unpack('>d', read_data[i+244:i+252])
                joint_p[0], = struct.unpack('>d', read_data[i+252:i+260])
                joint_p[1], = struct.unpack('>d', read_data[i+260:i+268])
                joint_p[2], = struct.unpack('>d', read_data[i+268:i+276])
                joint_p[3], = struct.unpack('>d', read_data[i+276:i+284])
                joint_p[4], = struct.unpack('>d', read_data[i+284:i+292])
                joint_p[5], = struct.unpack('>d', read_data[i+292:i+300])
                joint_v[0], = struct.unpack('>d', read_data[i+300:i+308])
                joint_v[1], = struct.unpack('>d', read_data[i+308:i+316])
                joint_v[2], = struct.unpack('>d', read_data[i+316:i+324])
                joint_v[3], = struct.unpack('>d', read_data[i+324:i+332])
                joint_v[4], = struct.unpack('>d', read_data[i+332:i+340])
                joint_v[5], = struct.unpack('>d', read_data[i+340:i+348])
                tcp_p[0], = struct.unpack('>d', read_data[i+444:i+452])
                tcp_p[1], = struct.unpack('>d', read_data[i+452:i+460])
                tcp_p[2], = struct.unpack('>d', read_data[i+460:i+468])
                tcp_p[3], = struct.unpack('>d', read_data[i+468:i+476])
                tcp_p[4], = struct.unpack('>d', read_data[i+476:i+484])
                tcp_p[5], = struct.unpack('>d', read_data[i+484:i+492])
                tcp_v[0], = struct.unpack('>d', read_data[i+492:i+500])
                tcp_v[1], = struct.unpack('>d', read_data[i+500:i+508])
                tcp_v[2], = struct.unpack('>d', read_data[i+508:i+516])
                tcp_v[3], = struct.unpack('>d', read_data[i+516:i+524])
                tcp_v[4], = struct.unpack('>d', read_data[i+524:i+532])
                tcp_v[5], = struct.unpack('>d', read_data[i+532:i+540])
                tcp_force[0], = struct.unpack('>d', read_data[i+540:i+548])
                tcp_force[1], = struct.unpack('>d', read_data[i+548:i+556])
                tcp_force[2], = struct.unpack('>d', read_data[i+556:i+564])
                tcp_force[3], = struct.unpack('>d', read_data[i+564:i+572])
                tcp_force[4], = struct.unpack('>d', read_data[i+572:i+580])
                tcp_force[5], = struct.unpack('>d', read_data[i+580:i+588])
                state,= struct.unpack('>d', read_data[i+1052:i+1060])  
                time_new, = struct.unpack('>d', read_data[i+4:i+12])
                break
    except:
        print('exp')

根据python代码，我在TwinCAT3中写了一个socket连接和读取功能块。但是，我现在在进行数据编码时遇到了一些问题：

FUNCTION_BLOCK DataEncoding
VAR_INPUT
    DataReceived: ARRAY[0..1115] OF BYTE;
END_VAR
VAR_OUTPUT
    moment: ARRAY[0..5] OF LREAL := [6(0.0)]; // LREAL stands for Double
    joint_pos: ARRAY[0..5] OF LREAL := [6(0.0)];
    joint_vel: ARRAY[0..5] OF LREAL := [6(0.0)];
    tcp_pos: ARRAY[0..5] OF LREAL := [6(0.0)];
    tcp_vel: ARRAY[0..5] OF LREAL := [6(0.0)];
    tcp_force: ARRAY[0..5] OF LREAL := [6(0.0)];
END_VAR
VAR
    i: INT;
    BYTEARR_to_STRING: BYTEARR_TO_MAXSTRING;
END_VAR

在正文部分：

FOR i := 0 TO 1116 BY 1 DO
    IF DataReceived[i] = 0 AND DataReceived[i+1] = 0 AND DataReceived[i+2] = 4 AND 
    DataReceived[i+3] = 92
        moment[0] := TO_LREAL(BYTEARR_to_STRING(in:= DataReceived[(i+204)..(i+212)]));
    END_IF
END_FOR

我遇到的问题是不知道怎么写字节数组和LREAL之间的转换。此外， DataReceived[(i+204)..(i+212)] 的数组索引似乎有一些错误。谁能教我如何在 ARRAY[0..1115] 中索引特定部分，如（204 到 212）？还有字节数组和LREAL的转换。

谢谢！

Answer 1

您可以将字节复制到 LREAL。
ADR()是获取变量内存地址的函数：

FOR i := 0 TO 1116 BY 1 DO
    IF DataReceived[i] = 0 AND DataReceived[i+1] = 0 AND DataReceived[i+2] = 4 AND DataReceived[i+3] = 92 THEN
        memcpy(ADR(moment[0]), ADR(DataReceived[(i+204)]), 212-204);
    END_IF
END_FOR