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MIW-RTVS1-EN-000 - 03 / 11 / 2020 9 - 12
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TRANSFORMER FAN SPEED CONTROLLER WITH
MODBUS RTU COMMUNICATION
RTVS1
Voltage steps selection
e standard configuration of the output voltages automatic mode is as indicated
in Table 1 below. e threshold levels at which each step activates is selected via
Modbus holding registers from 21 to 25. Each of these levels represents the value
above which step is activated.
Table 1 Voltage steps
Steps* 0 1 2 3 4 5
Auto forward
mode default
values
0 % 17 % 34 % 51 % 68 % 85 %
Auto reverse mode
default values -0 % 75 % 50 % 25 % 1 %
* Each level can take a value from 0 to 100 %.
OPERATING INSTRUCTIONS
NOTE On start-up the green COM LED blinks fast for 15 seconds to indicate that the
device is initialising.
■Make sure the connections are correct before you power the unit.
■Make sure the mains supply voltage is within the admissible rated maximum
current of the product.
ATTENTION
1. Switch off the mains power supply before connecting any power cables.
2. Install the connected sensor in an appropriate zone in order to measure the
relevant ambient conditions.
3. Select the operating mode via Modbus Holding Register 11. e default mode is
Automatic forward mode.
3.1 Manual mode
e value is taken by Holding Register 12, where you can set the desired
output step (see the steps and corresponding voltages in Table 1 above.)
3.2 Automatic modes
When Auto mode has been selected, the controller changes the five
speeds automatically according to the values measured by the sensor
connected to the RJ45 master socket. ere are two automatic modes:
3. 2.1 Automatic forward mode. See operational digram below:
Each level can take value from 0 to 100 % with the
following restrictions: 0 = OFF, i.e. the step is skipped.
For example: Step 1 = 17 %, Step 2 = 34 %, Step 3 =
0 %, Step 4 = 68 %, Step 5 = 85 %, from 34 to 68 %
the device will be in Step 2 and above 68% - in Step 4.
Each step threshold restricts by the steps above and below with
minimum of 11% difference, so when the hysteresis is set at 10%
the thresholds will not overlap. For example: Step 1 = 17 %, Step 2
= 34 %, Step 3 = 51 %, Step 2 can take values from 28 % to 40 %.
e Hysteresis delta is asymmetric, valid when the input value is
transitioningfromhightolowvalues.edevicewillsubtractthevalueofΔ
fromthestepthresholdandthestepwillchangebelowtheresultingvalue.
For example: Step 3 = 51 % threshold, Hysteresis delta =
2 %, Step 3 will be ON above 51% and OFF below 49 %.
An example of forward switching mode when Min
Step = 0 and Max Step = 5 is given in Fig. 4 below.
e thresholds are at 17 % and hysteresis delta is set from 2 to 10 %
via Holding Register 16 (see Fig. 4).
