Rockwell Automation 20-COMM-H RS485 HVAC Adapter FRN 2.xxx - Manual (Page 43)

Using Modbus RTU 4-11
20-COMM-H RS-485 HVAC Adapter User Manual
Publication 20COMM-UM009D-EN-P
store the returned 16-bit data. Use both 16-bit data items to make one 32-bit
value for drive parameter 12.
Writing Parameter Values
With a configurable output point, you can write a new value for any 16-bit
parameter in the drive. The sequence for writing parameter values is as
follows:
1. Set one or more Param# for OUTx points in the controller to the
parameter number(s) to which you want to write. A value of zero in the
Param# field disables the writing of data for that specific point. Refer to
the drive user manual for the desired parameter number(s). You can set
up to three Param# for OUTx points at a time. Refer to
Table 4.K on
page 4-12 .
2. Send a message with a Write Single Register (code 06) or Write
Multiple Register (code 16) function. You need to send the Param# for
OUTx point(s) to the adapter only one time per power cycle because,
when the adapter receives the Param# for OUTx point(s), it stores them
in its RAM.
3. Set the values that you want to write to the parameters in the User
OUTx points. You can set up to three User OUTx points at a time. Refer
to
Table 4.K on page 4-12 .
4. Send a message with a Write Single Register (code 06) or Write
Multiple Register (code 16) function. Each time that the adapter
receives the values in the User OUTx points, it writes them to the drive
parameters.
Figure 4.2 Configurable Output Point Operations
!
ATTENTION: Risk of equipment damage exists. If
configurable output points are programmed to write parameter
data to Non-Volatile Storage (NVS) frequently, the NVS will
quickly exceed its life cycle and cause the drive to malfunction.
Do not create a program that frequently uses configurable outputs
to write parameter data to NVS. Datalinks do not write to NVS
and should be used for frequently changed parameters.
Controller Adapter
and
Drive
Param#
for OUTx
Write Single Register (code 06)
or
Write Multiple Register (code 16)
User
OUTx
Write Single Register (code 06)
or
Write Multiple Register (code 16)