QUICKDESIGNER
Allen-Bradley
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37
WTC - Word Timer Counter
A WTC variable type is used to read a signed three digit BCD value from a timer counter word in the
PLC. The format of this word is shown below.
17 16 15 14 13 12 11 10 7 6
5
4 3
2
1 0
Not used
Done Bit (not used)
Sign Bit (not used)
Enable Bit (not used)
1's Digit
10's Digit
100's Digit
Example:
The following binary value is present in a PLC2/15 at timer 30, addressed as WTC30.
17 16 15 14 13 12 11 10 7 6
5
4 3
2
1 0
0
0
0
0
0
0
1
1
1
1
1
0
0
1
0
0
Reading this variable would result in the value 321 because the octal number in register 30 is 321.
Reading PLC-2 Data Highway Variables
The following illustration shows the format for reading variables from the Data Highway. The Data
Highway Address is a decimal value.
WUB00000/00_d
Bit Select 00-07, 10-17
Word Address
WUB Variable Type
Data Highway Address
When using the Data Highway, the following addresses are valid destination addresses, so long as a
PLC (not another computer) is at the destination address:
8 through 63 and 72 through 254 decimal
010 through 077 and 110 through 376 octal
The choice of addresses on the Data Highway greatly influences its speed of operation. Be sure to read
the Allen-Bradley documentation on the Data Highway, particularly those sections pertaining to
selection of module addresses and the polling scheme used on the Data Highway. In general, it is a
good practice to number Data Highway addresses consecutively.
