VEAB Heat Tech CV MODBUS Serie Handbuch Seite 16

CV ..-..-..MODBUS
Digital inputs
The digital inputs are activated when driven low (shorted to ground), their open circuit
voltage is 5VDC. They can be read from input status register address 1 and 2 .
As default factory setting they read as 0 when open and as 1 when activated (shorted to ground),
but can be set inverted.
Temperature sensing
The measurements from sensors on the analog inputs AI1/AI2 are stored in variables AI1 and UAI1,
accessed as input registers 4 and 5 . The values range from -4 000 to +10 000 since two decimals
are used. Unit is °C.
A reference resistor is built into the hardware and can be accessed as input register 6.
PWM pulse/pause output
The digital output DO2 is intended as a PWM pulse/pause output for control of the Pulser or TTC .
Both of the digital outputs may be configured for this purpose but only DO2 is equipped with a
MOSFET, while DO1 is a mechanical relay output with limited turn on/off cycles.
To activate pulse/pause for a digital output, three holding register variables need to be set:
DigOutXPulse DigOutXPulseTime , and DOX_CONF (replace X with output number).
DigOutXPulse contains the pulse length in percent. DigOutXPulseTime contains the pulse period,
i.e. the time between pulses, default is 60 seconds. DOX_CONF configures the output as pulse/pause
if set to 2 and regular output if set to 5.
The default setting for DO2 is pulse/pause and default setting for DO1 is regular output.
Note that the pulse length is set with two decimals only on DO2, which means that 7500 is 75%
while for the DO1 output 75 is 75%.
Offline action
To protect heaters, or equipment connected to digital outputs, in case of failure in the controlling
system, there is a built in monitoring feature that detects silence in the communication. The outputs
can be configured to shut off, if there has been no communication for 10 seconds. The configuration
is done by setting the corresponding DO*_CONF . To enable Offline action, i.e. to shut DO* off, in case
of communication silence, the value 128 must be added to DO*_CONF. The DO*_CONF registers are
normally 0, 2 or 5. In order to activate Offline action, they should instead be 128, 130 or 133.
Offline action is enabeled for all DOs, by default.
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