FANUC Robotics America GFK-1535A - Manual (Page 64)

GFK-1535A Chapter 5 Datagrams 5-3
5
Read Map
Subfunction Code: 2A hex
This datagram is used to read the reference addresses and lengths that have been
configured for the NIU's network I/O map.
Data Field Format: none
Read Map Reply
Subfunction Code: 2B hex
An NIU sends this reply datagram after receiving a Read Map datagram. It contains
the previously-configured NIU network map addresses. The network map defines
the NIU memory locations of the data that is exchanged on the bus. It provides no
information about the I/O assignments of individual I/O modules in the station.
However, the checksums indicate whether the overall configuration has been
changed.
Byte No. Byte Description
0 Not used
1 Starting reference for discrete input ( I ) data (LSB)
2 Starting reference for discrete input ( I ) data (MSB)
3 Length of discrete input ( I ) data (in bytes)
4, 5 Starting reference of analog input ( AI ) data
6 Length of analog input ( AI ) data (in bytes)
7, 8 Starting reference of discrete output ( Q ) data
9 Length of discrete output ( Q ) data (in bytes)
10,11 Starting reference of analog output ( AQ ) data
12 Length of analog output ( AQ ) data (in bytes)
13 8-bit Additive Checksum Unused (always 0)
14, 15 16-bit CRC Critical Checksum (lsb in 14, msb in 15) READ ONLY
16 8-bit Additive Checksum. Unused (always 0)
17, 18 16-bit CRC Non-Critical Checksum (lsb in 17, msb in 18) READ ONLY
Starting references in I, AI, Q, and AQ memory are returned. For each memory
type, a data length is also supplied. If a length is zero, the associated starting
reference can be ignored; it is not meaningful.