English
ERROR MESSAGES
• In case of alarm or malfunction, measure reading and alarm type reading may be
displayed alternately.
Operating alarm/error messages are described in the following table.
Message
Type of error
Output status
ER0
Sensor 1 disconnected or short-circuted
Same as in parameter (SUA)
ER1
Sensor 2 disconnected or short-circuted
Same as in parameter (SUA)
ALL
Minumim alarm
Depending on operation mode
ALH
Maximum alarm
Depending on operation mode
ALE
External input alarm
Same as in parameter (SUA)
OFF
Regulation blocked by external input
Same as in parameter (SUA)
Note:
The “OFF” message does not switch to the measure reading, but remains fi xed on
the display
SERIAL COMMUNICATION
• The device is fi tted with an isolated serial output RS-485
• The data communication system is based on MODBUS protocol and can be
connected to a Master system (PC/PLC)...) on a multipoint line RS-485:
- up to 32 FHT’s (slaves) without signal amplifi ers, from a maximum distance
of 1000m
- up to 247 FHT’s (slaves) in groups of 32 separated by proper signal amplifi ers
• Communication occurs in half duplex and only the Master (PC/PLC...) can initiate
Query/Response type transaction with the Slaves (only one slave with address) or
directing the message to all the slaves (address 0) without receiving an answer
• The MODBUS protocol specifi cations are:
- Coding system: RTU (Remote Terminal Unit)
- Transmission speed (Baud Rate): 9600, 4800, 2400, 1200 bps (can be selected by
user)
- Byte format: 1 start bit, 8 data bits, 1 parity bit (can be selected):
none, odd or even, 1 stop bit
• Contact TAS (Technical Assistance Service dept.) to request documents regarding
MODBUS functions and use of registers.
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User Manual – Thermoregulator FHT
