GE Industrial Solutions HE300GEN150 - Manual (Page 42)

MAN0373-01 13 APR 2000 PAGE 43
CH. 6
The starting address for the COMM_REQ is the first word in the first block move at %R100. Table 6.2 provides
an explanation of the values in the example that are either specific to the drive or change depending on the
COMM_REQ values. The values in the example are bold and are noted by superscript numbers that correlate
to the numbers in Table 6.2.
Table 6.2 – Superscript Notes for Ladder Example #2
Superscript
Number
COMM_REQ
Location
Name Description
1 Address Command Length Number of words from Address+6 to Address+n
2 Address+7 Device Number Device to receive COMM_REQ; 0-31
3 Address+11 Datagram Length
(Bytes)
Length of datagram content beginning at
Address+16
4 Address+15 Maximum Data Length This number must be large enough to
accommodate the reply message otherwise
data will be lost
5 Address+16 Starting Parameter
Number
(High byte)
High byte of word contains starting drive
parameter.
6 Address+18 Number of Parameter
Values to Read
(High byte)
High byte of word contains number of parameter
values, in bytes, to read from the drive.
The description of the reply datagram from the drive is contained in Table 6.3. A general description can be
found in the Series 90-30 Genius Bus Controller User’s Manual (GFK-1034).
Table 6.3 – Reply Datagram Description
COMM_REQ
Location
Name Description
Address
Data Length in Bytes (High Byte)
Device Number (Low byte)
The high byte of the word contains the total number of
bytes in the reply and the low byte contains the device
number where the reply originated.
Address+1
Subfunction Code (High Byte)
Function Code (Low Byte)
The high byte of the word contains the Subfunction
code and the low byte contains the Function code of
the reply datagram.
Address+2 Starting Parameter # (High Byte)
Always 0 (Low Byte) The high byte of the word contains the starting
parameter number and low byte is always 0.
Address+3 Always 0 The word is always 0.
Address+4 # of Data Bytes (High byte)
Always 0 (Low Byte) The high byte of the word contains the number of data
bytes and the low byte is always 0.
Address+5 to
Address+n
Drive Parameter Value(s)
The word contains the value for request drive
parameter number.
6.4 PLC Ladder Code
In Examples 1 and 2, the COMM_REQ requires four inputs; Power, IN, SYSID and TASK. The Power input is
assigned to a contact that is on for only one scan. Leaving this contact on causes the datagram to be sent
multiple times and slows down the response time on the Genius LAN. The IN input is set to a %R reference that
contains all of the registers determined in the examples. The SYSID input specifies which rack and slot has the
Genius Bus Controller that receives this command. The upper byte is the rack number and the lower byte is the
slot number. The value of 0005 in the examples represents rack 0 slot 5. The TASK input is always set to a 1.