Specifications

Section 2—Modbus Plus Overview Bulletin No. VVDED397044US R12/00
Global Data Transmission December 2000
46
© 1998–2000 Schneider Electric All Rights Reserved
GLOBAL DATA TRANSMISSION
When a networked node holds the token, it may communicate with other
nodes on the link and gather network statistics. When a node releases
the token, it appends up to 32 sixteen-bit words of global data to the token
frame. All nodes present on the network detect this data packet, and any
appropriately programmed node can extract the data and record it in its
global database. For a MODBUS PLUS network with a maximum 64
nodes, the global database can contain up to 2048 sixteen-bit words (32
words per node). Different networks cannot share global data since the
token cannot pass through a bridge.
If global data transmission is enabled for the ATV58 drive controller, up to
32 display registers of the drive controller can be broadcast to the
network as global data with each token rotation. To enable global data
transmission, enter the number of display registers to be transmitted in
the ”Global Tx” field of the 8—Communication menu (see Table 8 on page
36). Entering “0” in this field disables global data transmission.
Table 14 on page 46 lists the display registers transmitted as global data,
their addresses in the drive controller, and the order in which the registers
are transmitted in global data transfers. For example, if 8 is entered in the
Global Tx field of the 8—Communication menu, the first eight display
registers (words 2041–2048) will be broadcast as global data each time
the drive controller passes the token.
Table 14: Display Register Mapping w/ Global Data
Global Data
Order
Number
Address of
Drive
Controller
Variable
Designation Description
1 450 FRH Frequency reference
2 451 RFR Output frequency applied to motor
3 452 SPD Motor speed estimated by drive controller
4 453 LCR Current in motor
5 454 ULN Line voltage (via bus)
6 455 THR Motor thermal state
7 456 THD Drive controller thermal state
8 457 LFT Last fault to occur
9458ETA
DRIVECOM drive controller status
register
10 459 ETI
Drive controller internal status register
No. 1