Yaskawa MicroTrac Gateway to Allen-Bradley Data Highway Plus for use with Microtrac LAN User Manual
Page 6
Introduction
6
Drive Description
3
SOFTWARE
SOFTWARE
SOFTWARE
The EPROMs on the CPU card contain a software program that is fixed (i.e.
not changeable on a job-to-job basis), and is transparent to the user. The
software allows communication between MicroTrac drives and the Allen-
Bradley Data Highway Plus network via teh NUMO PAC block which outputs
numeric data from the DSD drives to PLC block transfer reads (BTRs).
The PLC gateway, when connected to the Allen-Bradley Data Highway Plus
cable, can be treated as if it were an Allen-Bradley PLC5 at station address 4
on the network. The gateway provieds access to file number N11 for other
PLCs on the Data Highway Plus Network.
The channel and sub channel numbers used by the NUMO PAC block define
the item number in DHP file N11. The item number equals the channel
number times ten (10) plus the sub channel number:
(Channel Number * 10) + Sub channel Number = File offset
For example, to address item 113 in file N11, the NUMO PAC block would
use channel 11 and sub channel 3, i.e. (11 * 10) + 3 = 113. To address item
241, the NUMO PAC block would use channel 24 and sub channel 1, i.e. (24 *
10) + 1 = 241.
The node number used by the PAC block to address the PLC gateway is
usually 200, as discussed in the previous section describing the Network
Interface card setup.
Each Numeric data item uses one 16 bit word in the PLC file. The word is
presented to the DHP network as a two’s complement binary number (also
called a signed integer). These numbers can range from +32767 to –32768.
These integer values might have an assumed fixed location for a decimal point.
Since the number transferred to or from the PLC is an integer, not an integer
plus a fraction, there must be some way of determining where the decimal
point is to be located. In the numeric PAC block NUMO, this is accomplished
by the DP (decimal point) parameter. For example, if the integer transferred
from the PAC block to the PLC has a range of +32.767 to –32.768, the DP
parameter for that PAC NUMO block must be specified as three (3).
OPERATION
RD 906-20
© 1994 MagneTek, Inc.
94-04