GE Industrial Solutions HE300GEN150 - Manual (Page 38)

MAN0373-01 13 APR 2000 PAGE 39
CH. 6
CHAPTER 6: DATAGRAM ACCESS
6.1 General
Global and directed data are the standard methods used to send and receiving drive parameter data.
Datagrams can also be used to send and receive drive parameter data. Sending and receiving data using
datagrams is done using a communications request (COMM_REQ) in the PLC logic. There two
communications requests that are support by the drive card, Write Device (20H) and Read Device (1EH). The
specifics on using communications requests are found in the Series 90-30 Genius Bus Controller User’s Manual
(GFK-1034) or refer to Appendix A for the Write and Read datagram COMM_REQ values. The following
sections describe specific portions of the datagrams that are specific to communicating with the option card.
6.2 Write to Drive using Datagram
The Send Datagram COMM_REQ (14) is used to send a Write Device datagram. The Write Device datagram is
used to write from the PLC to parameters in the drive. The COMM_REQ allows multiple sequential parameters
to be written. A starting parameter number is supplied, the number of parameters and the values of the
parameters. The following is an example of a Write Device datagram to set the drive speed to 30.00Hz
(Figure 6.1).