Allen-Bradley DeviceNet 1761-NET-DNI, User Manual, Page: 57 / 101

1761-6.5
DNI Configuration Parameters and Programming Notes 5-23
Status Byte
The first byte (bits 0 to 7) of the first word of I/O data is set aside as status
information. The second byte (bits 8 to 15) of the first word of I/O is
available for user data. The DNI Input/Output Image is shown below:
Input Status to Master Device
The Input Status Byte provides the following information:
Output Buffer Overdrive (Bit 6, written by the DNI)
This bit is set (1) when Master Outputs arrive at a rate faster than the DNI
can forward the data to the DF1 device. When the Buffer Overdrive bit is
set, the output image is being overwritten before it can be sent to the DF1
device. To resolve this, limit the data production rate in the scanner until this
bit stays clear (0).
Word Input/Output Image
Series A Series B
0
0 Data (bits 8 to 15) Status Byte (bits 0 to 7)
1 1 Data Most Significant Byte (MSB) Data Least Significant Byte (LSB)
2 2 Data MSB Data LSB
3 3 Data MSB Data LSB
↓ ↓ ↓ ↓
14 30 Data MSB Data LSB
15 31 Data MSB Data LSB
Function n/a Output Buffer Overdrive n/a
Bit Number 7 6 5 4 3 2 1 0
AB Parts