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Taylor™ Programmable Controller Interface User’s Guide
Section 4.6.4 Techniques to Maximize CCF Output Grouping
Constraints on Grouping
SCA commands cannot write to an area of the PC that is being referenced by another command.
This is to prevent the SCA value from being cleared by and output from the MOD 300 System.
Example 1 (for a MODICON):
Cmd
Start
Num
Words
Type
Channel Rate
ROC
1
10
D
1
5
ROR
1
20
A
1
5
DFOA
200
5
D
161
5
SCAC
280
5
This command is valid since the SCAC does not write to an area of the PC that is already used
by another command.
Example 2 (for a MODICON):
Cmd
Start
Num
Words
Type
Channel Rate
ROC
1
10
D
1
5
ROR
1
20
A
1
5
DFOA
200
5
D
161
5
SCAC
279
5
This command is not valid since the SCAC writes to a coil inside the range referenced by the
DFOA.
For a PC on a TIWAY, a CRWA cannot be in the middle of a block of reads. A block is a set of
consecutive reads that totals no more than 64 words.
Example 1 (for a TIWAY):
Cmd
Start
Num
Words
Type
Channel Rate
DPDI
1
16
D
1
5
DPDO
1
16
D
257
5
DPCR
1
32
D
513
5
These commands are combined into a block since the total number of words read is not greater
than 64.
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