ReadHoldingRegisters takes 2seconds

[JODLatGit]

I am using a Seneca Z-8NTC to readout NTC's resistors. I have seen that underneath commands:

// Read 16 registers starting at 74)
waitPeriod = millis();
result = Modbus1.readHoldingRegisters(74, 16);
waitPeriod1 = millis();
if (result == Modbus1.ku8MBSuccess)
  {
  NTC2 = Convert4bytesToFloat(2);  (In the function I use getResponseBuffer)
  NTC4 = Convert4bytesToFloat(6);
  NTC6 = Convert4bytesToFloat(10);
  }

The command readHoldingRegisters takes up 2 seconds ? It of course slows down the response time of my Controllino application .

The serial settings are :

// Init RS485 Controllino_RS485Init(19200); //NTC module Modbus1.begin(2, Serial3 );

Do I something wrong ? What can I do to let it response faster ? It is always almost exactly 2 seconds measured with the millis() function.

ModbusMaster version

[Version : 2.0.1]

Arduino IDE version

[Version : 1.8.19]

Arduino Hardware

[Controllino Max]

[JODLatGit]

Did another test instead of reading 16 registers I read only 2 but the execution time stays the same 2 sec . It seems that readHoldingRegisters cmd takes up 2 seconds ??

[JODLatGit]

Another test learns me that apparently changing underneath the value from 2000 to 50 in the header file the readHoldingRegisters command response in 50ms instead of the 2000 !!?? // Modbus timeout [milliseconds] static const uint16_t ku16MBResponseTimeout = 50; ///< Modbus timeout [milliseconds] Seems that the readHoldingRegisters command isn't working properly !!! Took almost 1 day to solve it.

[rob040]

Another test learns me that apparently changing underneath the value from 2000 to 50 in the header file the readHoldingRegisters command response in 50ms instead of the 2000 !!?? // Modbus timeout [milliseconds] static const uint16_t ku16MBResponseTimeout = 50; ///< Modbus timeout [milliseconds] Seems that the readHoldingRegisters command isn't working properly !!! Took almost 1 day to solve it.

That is not a solution, but a workaround. Still, if your implementation is hit by the timeout, be it 2 or 0.05 seconds, then there is something wrong with your communication or modbus slave. please check the return value of readHoldingRegisters (). It should be 0 on success, but will be ku8MBResponseTimedOut (0xE2) in case of timeout.