Recent posts to Are Modbus Holding Registers writable from PLC?https://forge.codesys.com/forge/talk/Engineering/thread/90d10412d7/2021-11-08T15:22:11.901000ZRecent posts to Are Modbus Holding Registers writable from PLC?Are Modbus Holding Registers writable from PLC?2021-11-08T15:22:11.901000Z2021-11-08T15:22:11.901000ZUlvishttps://forge.codesys.com/u/ulvis/https://forge.codesys.com4fb0490a11d5a8a2a753c1499567b4ea11f1f6fb<div class="markdown_content"><p>Yes, Indeed. The problem was that the register items were still of type %IWx, i.e. read only registers.<br/>
Only after deleting the mapped variables and fiddeling with the number of registers setting in the 'General' tab, did the type change to %QWx, for writable registers. The user-program can now clear the received registers after processing.<br/>
<a class="user-mention" href="/u/i-campbell/">@i-campbell</a>, Thanx.</p></div>Are Modbus Holding Registers writable from PLC?2021-11-04T18:57:13.141000Z2021-11-04T18:57:13.141000ZUlvishttps://forge.codesys.com/u/ulvis/https://forge.codesys.com4182e210a3d59d24baeccbe8a2dd5459c486cda4<div class="markdown_content"><p>That has been tried, but I will try again.</p></div>Are Modbus Holding Registers writable from PLC?2021-11-04T18:50:41.106000Z2021-11-04T18:50:41.106000Zi-campbellhttps://forge.codesys.com/u/i-campbell/https://forge.codesys.com72035c32d5de66da83ab28cef7392ebb2ab27bad<div class="markdown_content"><p>There is a checkbox on the General Tab next to holding registers named "Writeable", which makes them writeable by the PLC.</p>
<p><a href="https://help.codesys.com/webapp/_mod_edt_slave_device_com;product=core_modbus_configuration_editor;version=3.5.17.0" rel="nofollow">https://help.codesys.com/webapp/_mod_edt_slave_device_com;product=core_modbus_configuration_editor;version=3.5.17.0</a></p></div>Are Modbus Holding Registers writable from PLC?2021-11-04T16:28:41.127000Z2021-11-04T16:28:41.127000ZUlvishttps://forge.codesys.com/u/ulvis/https://forge.codesys.comb6dab6ad4c4e21002c4eb07a2bd6a490fecf7a80<div class="markdown_content"><p>It appears that Holding Registers are writable only from Modbus. These are then mapped to Codesys PLC variables. Is this mapping one-way only?<br/>
For values updatable by PLC code I have used Input Registers.<br/>
Is this by design?<br/>
i.e. Scada (client) --> Modbus --> Holding Registers --> PLC (server)<br/>
and Scada (client) <-- Modbus <-- Input Registers <-- PLC (server)</p>
<p>Can Holding Registers be cleared in the PLC by PLC code? E.g. to clear a recieved command word after execution of local code.</p></div>