CleaverBrooks Hawk 1000, Operation Manual

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Hawk 1000 Section 4 — System Configuration
Part No. 750-366 4-15
4.4.5 Remote Modulation/Remote Set Point
Signals for Remote Modulation or Remote Setpoint can be provided by either an analog input signal or written
directly into the PLC by communications (Ethernet).
Figure 4-14. Remote Mod/Setpoint by Communications
Remote Modulation by Analog Input
This configures the Boiler Controller to receive a remote 4-20mA signal on input I:2.3 to control the firing
rate of the boiler.
The signal is scaled from 0-100%, (4ma = Low Fire and 20ma = High Fire).
Remote Modulation by Analog Input Signal Selection
The user can select between HMI or digital input to enable Remote Modulation.
Select <Digital In> if another control system will enable Remote Modulation by isolated contact input signal
(120 VAC) on digital input I:5.14. When that input is de-energized, the Boiler Controller will revert back to
local firing rate control. If Remote Modulation operation will be enabled manually, select <HMI Input>.
Remote Modulation can then be enabled, by selecting the <Remote> button on the Firing Rate Screen.
If the PLC detects a bad analog signal, an alarm “Remote Modulation Signal Failure” is activated and the Firing
Rate revert to the LOCAL setting on the HMI.