NOTES FOR REMOTE PROGRAMMING
The writable registers are shown in TABLE MODBUS MAPPING referred to as W or RW (write or read / write) max number
of registers 72, see table page. 20.
In the case in which the channel is not enabled and / or the information is not provided we have the following answers:
1. Temperatures measured = 0000 (0 ° C)
2. Temperatures AL. / TRP = value written in E2PROM
3. Channel status = 0000
4. Setting channel =% 00000000, xxxxxxx0% (x = na)
If WRITE data must always respect the rule T_trip> T_alarm and FAN_ON> FAN_OFF.
In case you try to set these thresholds incorrectly, the control unit NT538 ETH will not proceed with the programming and
storage of data, therefore in subsequent readings will read the data from the previous schedule.
After having sent a request for writing the control unit will take a time of about 1 '' to store the data in eeprom, during the step
of storing the module ModBus will not be able to process additional requests.
If the demand for programming is successful, the unit automatically resets and loads the new settings.
In the event that information is sent in writing to a register can’t be written (only READ) data will be trashed without affecting
the received message.
The information "RELAY STATUS" indicates the state of excitation of the coils of the relays, so it will be subject to the
commands of "FAIL SAFE".
From the point of view of the control unit Modbus connection is considered as a normal NT538.
At the end of the write command (Write) is carried out a check of compatibility data:
If you have a non-compatibility "exception" for an answer and the data packet is rejected in its entirety. The code
of the first erroneous data can be obtained by reading the log "Error received data" (Note: this code is lost during
RESET or new power or writing data in E2PROM);
if the data are correct, they are transferred to the non-volatile memory (E2PROM), resets the historical data (Tmax
= 0 ° C) and is subsequently forced a reset of the system
If the WRITE command implies only writing "CONTROL" it will be implemented autonomously and without RESET,
ie without affecting the data of the control unit.
ERROR CODES (exception codes)
In case of a wrong request, ModBus will answer with modified codes and codified errors according to the following:
1: - Unsupported function code
2: - Wrong data address
3: - Wrong data (for instance length)
The memory area containing the HFN datum must undergo no forcing.
In the case in which all the fans are turned off (F1, F2) the test of the relay will not take place.
GENERAL UNIT NOTE
The models of the unit can be equipped with different options; to avoid disruption of production their existence is defined by
Fw indicated power , with messages dedicated on display LEDs .
This information can be accessed by reading the Modbus register 6 (options) with the following meaning:
LOW Byte
Bit_1 = Ethernet
HIGH Byte
Bit_0/1 = 00 - Range 0°C ÷ 240°C
Bit_0/1 = 10 - Range -40°C ÷ 200°C
In case of Ethernet option Modbus and 4.20mA mode shall not be active on the display. They will be readable from the log.
Note: in case the values programmed from ModBus are out of range, it will generate a "exeption" error response to
date.
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