%MX0.2019.3= modbus address DEC 16155 2019*8 + 3 = 16155
%MD0.17 occupies two modbus addresses DEC 34 and DEC 35
17*2 = 34 and next one
https://gyazo.com/d5fc76f1b81ff3d8b05... (ignition information)
I know standard modbus AI: %IW (analog input 30001 -39999)
DI: %IX (discrete inputs 10001-19999)
DO: %QX (discrete out 1-9999)
AO: %QW (analog out 40001 - 49999)
I am looking for the holding registers and such for the AC500. Is there a map leading to decimal value. If %MD0.3 is in DEC 6 and 7. Does that mean it's under the DO(coil section). I do know the PLC uses an MFM (power meter) how would that affect modbus addressng
If you want to read holding registers of Ac500 from external modbus master, you have to find how (and from where) that master is reading holding registers.
Usually holding registers are read with 40xxx, in your case that should be addresses 40006 and 40007. But all that depends on how that is organized in you modbus master - look for command or address area, where it is reading holding registers.
For example AC500 uses COM_MOD_MAST block with FCT=3 or 4 and start address 6 and 7.