Latching and Non-latching

In the context of Modbus, manufacturers often use the terms latching and non-latching registers to describe the behaviour of registers in terms of how they retain their values after power is removed. However, it is important to note that the Modbus specification does not formally define these terms, and manufacturers may interpret them differently.

For example, some manufacturers may define latching registers as registers that retain their values even after power is removed. Other manufacturers, however, may define latching registers as registers that retain their values until someone explicitly overwrites or resets them, regardless of whether power is removed. Similarly, some manufacturers may define non-latching registers as registers that do not retain their values after power is removed, while others may define non-latching registers as registers that retain their values until someone explicitly overwrites or resets them, regardless of whether power is removed.

Manufacturers often use the terms latching and non-latching registers to describe the behaviour of registers in Modbus, but their specific definitions may vary. Therefore, it is important to carefully review the documentation provided by the manufacturer of a Modbus device to understand how these terms apply to the registers on that device.