100/180 mm PAPERLESS GRAPHIC RECORDER: USER GUIDE
User Guide
Page 177
HA028910
Issue 13 Sep 16
4.3.18 DEMAND WRITES (Cont.)
WRITING TO A SPECIFIC REGISTER
When ‘User Defi ned’ is selected , or if the slave device is ‘Unknown’, then a register can be defi ned which
can be written-to directly. The register addresses must be found from the documentation supplied with
the slave device.
Figure 4.3.18c Demand Writes to specifi c register
CONFIGURABLE PARAMETERS
This contains details of parameters unique to Demand Writes to specifi c registers. Other parameters are
as described above.
Function Code
Allows the Modbus function code 6 or 16 to be selected. See the documentation
supplied with the slave for a list of supported Modbus codes (for this instrument see
section 8.2.1
). Demand writes of a single 8 or 16-bit register can use either code, but
code 6 is more effi cient. Writing two or more registers requires the use of code 16.
Register
A decimal number representing the required parameter’s location in the slave’s
Modbus Register map. This information must be determined from the documenta-
tion supplied with the slave. For this instrument,
section 8.4
contains listings for a
number of instrument, groups, and input channels. For details of maths, totalisers
etc., refer to the relevant option description.
Data Type
Select a suitable data type for the selected parameter (again from the slave docu-
mentation). For this instrument, a list of relevant data types is given in
section 8.4
.
Enable
Demand Type
Status
Master Comms
Apply
Discard
Write number
1) Write 1
Select the Write to
be configured
Select 'Master
Comms' or 'Off'
Idle
Demand Write
Slave
1) Furn 1 Recorder
Select destination
slave
Parameter
User Defined
Function Code
Register
248
Data Type
Source
Constant
Enter default value
Default
0
Allow Constant Edits
Disable Retries
Send On Power Up
Allows user to edit the constant prior
to write (if Source = 'constant')
If enabled, the write is attempted only once.
Write is triggered when the unit powers up.
Descriptor
Write 1
Preset Multiple reg (16)
Float (32 Bit)