Gill Instruments Ltd
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MetPak/MetPak RG and MetPak Pro
Page | 53
Issue 1
Doc. No. 1723-PS-0022
October 2018
6.3.
Polled Mode
6.3.1 To Configure a MetPak Unit for Polled Mode:
Connect a default set MetPak Unit to a PC as described in Para 4.9.
Open MetSet as described on Para 6.2.
Click on the Edit Comms page and select:-
Set Protocol for required poll mode interface e.g. RS485P2W and
Set Message Mode to Poll.
Click on Save Settings to Device on the Online Mode Menu.
Shut down the MetPak unit.
Change the hardware connections for the required Poll Mode Interface.
E.g. RS485P2W in para 4.11.
6.3.2 Using Polled Mode:
When in the Polled mode, an output is only generated when the host system sends a Poll signal to
the MetPak Unit consisting of a ? Character followed by the MetPak Unit Node ID – that is, the
relevant letter A – Z.
The commands available in Polled mode are:
Description
Command
Base Station Response
Enable Polled mode
?
(None)
MetPak Unit ID
A ….. Z
Data output generated
Disable Polled mode
!
(None)
Request MetPak Unit Identifier
?&
A ….. Z (as configured)
It is suggested that in polled mode the following sequence is used for every poll for information.
?
Ensures that the Sensor is enabled to cover the event that a power down has occurred.
A-Z
Appropriate unit designator sent to retrieve a line of data (default is Q).
!
Sent to disable poll mode and reduce possibility of erroneous poll generation.
When in polled mode the system will typically respond to the data command within 30mS with the
last valid data sample when set for 1Hz output rate.
If a Wind Sensor is not connected to the MetPak Unit then allow at least 3 seconds for a poll
request reading output.
If the unit is powered down after use or upon switch on then allow 10 seconds from switch on
before sending poll commands.