GE PACSystems RX7i - SVC_REQ 6: Change;Read Number of Words to Checksum; To Read the Word Count; To Set a New Word Count

Chapter 6. Service Request Function
284 PACSystems* RX7i, RX3i and RSTi-EP CPU Programmer's Reference Manual GFK-2950C
6.7 SVC_REQ 6: Change/Read Number of Words to Checksum
Use SVC_REQ 6 to read the current word count in the program to be check-summed or set a new
word count. By default, 16 words are checked. The function is successful unless some number other
than 0 or 1 is entered as the requested operation.
The parameter block has a length of 2 words.
6.7.1 To read the word count:
Enter a zero in the first word of the parameter block.
Address
0
Address +
1
Ignored
The function returns the current checksum (word count) in the second word of the parameter block.
No range is specified for the read function; the value returned is the number of words currently being
check-summed.
Address
0
Address +
1
Current word count
6.7.2 To set a new word count:
Enter a one in the first word of the parameter block and the new word count in the second word.
Address
1
Address +
1
New word count
The CPU changes the number of words to be check-summed to the value given in the second word of
the parameter block, rounded up to the next multiple of 8. To disable check-summing, set the new
word count to 0.