NPM Motionnet G9001A, User Manual

Page: 25 / 125

DA70131-1/3E
I-19
4-5-2. "Cyclic communication error flags" area
The center device communicates with all the I/O ports using cyclic communication.
In this type of cyclic communication, if a communication error occurs for a specific I/O device (G9002A) on three
consecutive communication cycles, the center device will treat this as cyclic communication error.
When this error occurs, the bit in this area corresponding to the device number will become 1. By checking these
bits, you can identify the I/O device (G9002A) in error.
Ex.: When reading address 0B8h
For a 16-bit CPU (address = 0B8h)
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
As seen above, the lowest bit shows the error status of the local device with the lowest address number. By reading
"0B8h," local device numbers from 0 to 15 can be checked. In the same way, by reading "0BAh" you can check
device numbers 16 to 31.
To determine the address, proceed as follows. (discard any remainder)
Address = 0B8h + (Device No. / 8)
For an 8-bit CPU (address = 0B8h)
7 6 5 4 3 2 2 1 0
The bits are read in groups of 8 by an 8-bit CPU, but the meaning of each bit is the same.
The device number refers to the number allocated to each local device. The numbers are specified on the external
terminals on local devices. Duplicate use of the same number is prohibited.
- To clear flags
In order to return a bit to 0 that was changed to a 1 when an error occurred, write a 1 to this bit.
The simplest way to clear a flag is to write the same data back to the same cyclic communication error flag position
that it was read from.
(For examples of how to use these flags, see point (2) in the "Check and Clear Errors of any existing input-change
interrupts" in "Software examples" in Chapter IV.
Error on device number 15 Error on device number 15
Error on device number 7
Error on device number 0