Read boolean

[iotgopher]

please can you advise if there is a function to read booleans?
@robinson

[robinson]

@RTmaster read boolean is similar with read any types of data:
buf := make([]byte, 255)
err := client.AGReadDB(address, start, size, buf)
if err != nil {
t.Fatal(err)
}
here you got the the buf, which is an array of byte, then just get the value from buf:
var s7 gos7.Helper
var result boolean
s7.GetValueAt(buf, 0, &result)
Now you got the result is a boolean.
Cheers, R

[sandeep51989]

I see there to be a problem with this approach. If the boolean is given in a byte it works. How can we have get booleans at the bit position in a byte. For example if i want to get the boolean value at 180 the position at bit 6.

According to examples given.
s7.GetValueAt(buf, 180, &result)

All the function does is read the record at position byte 180 but how do we get the value at the bit position off the byte.

[robinson]

@sandeep51989: more specific: the buf is an array of bytes which stores the return values - maybe: bool, int8, int16...so on. The values arrange from the position 0. The helper: S7.GetValueAt will return an interface of value.

[pizzalord22]

sorry for reviving this old thread but when i read a byte containing 8 bool bits it returns 1 byte in the buffer array instead of 1 byte for each bool value. so i can not get individual bool values

[petar-dambovaliev]

@pizzalord22
This will give you the specific boolean you want from the byte.
myBool = (byte & (1 << bitPos-1)) != 0;

[petar-dambovaliev]

I have added the boolean support in the helper.
#17

[sunblack110]

It's good , but how about write a boolean to PLC, do we need to read it in a byte first, then change a bit in the byte, then we write to PLC , it's not a good idea.