Allow/Enable a customizable delay between each Modbus request.

[ziotibia81]

Currently, consecutive Modbus requests are sent directly without a delay.

This feature could be very useful. Some devices that implement Modbus RTU over TCP internally consist of a TCP-to-Serial converter connected to the device's microprocessor. In this scenario, it is important to have a delay between each request. Reading many consecutive registers in a singlerequest is more efficient with this type of device.

Originally posted by @ziotibia81 in #1589

This feature is also necessary when reading from multiple devices connected to an RS485 bus with a Modbus RTU to TCP bridge. A delay between each request is required to allow the devices time to internally switch their transmitters to high-impedance mode (HI-Z) and release the bus.

[imbeacon]

Hi @ziotibia81,

Thank you, for your interest in ThingsBoard IoT Gateway.
I have added parameter delayBetweenRequestsMs and processing for it to master, it allows to set delay between requests to device. Needs to be configured for each device separately, on the same configuration level, where you set port for connection.
By default it is set to 0 and doesn’t affect current processing.
In order to use it you can try the version from the master branch or wait for release. We are going to publish new release in few days.