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11.7 Error messages
The controller shows an error message, if the measured temperature is outside the limits or there is no connection to the sensor.
The following messages may appear:
Value
Description
LO
Measured value at AI less than low limit 0°C
HI
Measured value at AI exceeds high limit 80°C
ERR
Error: short circuit or open connection at AI
12. Modbus communication protocol PAW-FC-RC1
The Modbus protocol is a general-purpose protocol for data exchange between for instance control units, Building Management
Systems, instruments and electricity meters. It's an asynchronous, serial Master Slave protocol. It's widely used, well documented
and simple to understand. A Modbus master can communicate with up to 247 slave units with the device ID 1-247. A protocol like
Modbus consists of several layers (OSI-model). The bottom layer is always the physical layer; the number of wires and signal levels.
The next layer describes the communication digits (number of data bits, stop-bits, parity etc.). Next are the layers describing the
Modbus-specific functions (number of digits per message, the meaning of different messages, etc.).
12.1 Modbus register types
1.
Discrete Input Register
2.
Coils Register
Supported Modbus functions:
✓ 0x01 Read Coils
✓ 0x02 Read Discrete Inputs
✓ 0x03 Read Holding Registers
12.2 Discrete Input Register
Variable address
Description
1
Not used
2
Not used
Presence detected
0 = Presence not detected
3
1 = Presence detected
Active if presence detector is configured at terminal DI.
Change-over heating/cooling
4
0 = Change-over heating
configured at terminal DI.
Fan speed 1
5
0 = Fan speed 1 is not active on DO FAN1
1 = Fan speed 1 is active on DO FAN1
Fan speed 2
6
0 = Fan speed 2 is not active on DO FAN2
1 = Fan speed 2 is active on DO FAN2
Fan speed 3
7
0 = Fan speed 3 is not active on DO FAN3
1 = Fan speed 3 is active on DO FAN3
Heat valve
8
0 = Heat valve is not active on DO Heat
1 = Heat valve is active on DO Heat
Cool valve
9
0 = Cool valve is not active on DO Cool
1 = Cool valve is active on DO Cool
Indicates the current change-over state of the controller 0 = Heating 1 = Cooling
10
This value may be set by either DI or Temp change-over control
11-19
Not used
20
Actual value on DI, before filters such as NC/NO
21
Not used
22
Actual value on DO FAN1, after filters such as NC/NO
23
Actual value on DO FAN2, after filters such as NC/NO
24
Actual value on DO FAN3, after filters such as NC/NO
25
Actual value on DO Heat, after filters such as NC/NO
26
Actual value on DO Cool, after filters such as NC/NO
To do
Check the temperature of the pipeline and the value of the
disconnected sensor (must HI Measured value at AI exceeds high
limit 80°C be between 1kΩ and 1,309kΩ)
Check the cable between controller AI and the sensor
✓ 0x04 Read Input Registers
✓ 0x05 Write Single Coil
✓ 0x06 Write Single Register
1 = Change-over cooling Active if Change-over sensor is
30
3.
Input Register
4.
Holding Register
✓ 0x0F Write Multiple Coils
✓ 0x10 Write Multiple Registers
✓ 0x17 Read/Write Multiple Registers
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