Upon selection of "Write" option, the Write Dialog is shown. Depending on the Data Type settings two types of write dialog boxes are shown. See image below. The dialog box on the left is shown when the Function is set for all except Coils. When the Function is selected as Coils (0x), the dialog box on the right is displayed. The write values on both values on both dialog box are different. On the registers, simply enter the value in the Write Field and click Change button. On the Coils, check or uncheck the coils that need to turn on or off, accordingly.
The Modbus Monitor Advanced offers one other useful options for the system integrators and troubleshooting. The "Increment" feature for the register increments the (writes) the values automatically from programmed range (low to high). The "Toggle" feature on the coils automatically toggles (writes) all coils to opposite values.
Note that the Write Dialog box is shown during Master and Server modes. During the Master operation the write value is stuffed into the Modbus packet sent to request to remote server (using the Write Function selected). During the Modbus Slave operation, the write value is stored internal registers and waits for the remote master to poll for that registers. Once polled, the write values is taken out of internal memory and stuffed into Modbus packet sent to remote Modbus Master.