WDV Write Remote Digital Value Function Block
Write Remote Digital value (WDV) function blocks allow any digital value to be transmitted to other devices on the network in a peer-to-peer fashion. Values can be transmitted with the MBus_ioFlash protocol or with the Modbus protocol. Adding WDV blocks to a device will make that device behave as a Modbus Master on the RS485 network it is connected to. You can add several WDV blocks in combination with WAV and SCAN blocks on the same device, communications will be managed automatically so there are no collisions.
** Important note: on an RS485 network there can only be one master device, otherwise communications from one master would collide with the other. Therefore you must make sure that the WAV blocks are only used an a device that will be designated as Master the RS485 network it is connected to. You should deactivated the block (see Scan On parameter below) before attempting remote communications from MBus_ioFlash or any other Modbus Master on the RS485 network.
|Name||Function block name, see common parameters|
|DYN dynamic option, see common parameters|
|Input||This is the input parameter that the block will transmit to remote devices. The value is monitored and if it changes the new value is transmitted to the remote device.|
|Scan On||Digital input to control whether the WDV block is active or not. See note above.|
|Rate||Determines the maximum rate that new values will be transmitted. If the input value is constantly changing this this parameter can be used to limit the amount of data transmitted on the RS485 network.|
|Network Parameter: MBus_ioFlash / Modbus||Determines the protocol to use to transmit the value to the remote device. If Modbus is selected the the Modbus command "(0x05) Write Single Coil" is used.|
|Network Parameter: Dev addr||Modbus address of the device on the RS485 network that receive the analog value.|
| (MBus_ioFlash protocol
Network Parameter: Block name
|The name of the block within the target device's MBus_ioFlash program.|
|(Modbus protocol selected)
Network Parameter: Reg No.
|The Modbus register number within the target device's register space. Note that base(1) numbering is assumed.|