I have next-to-no experience working on Omron CJ-series PLC's so bear with me. When I'm assigning Unit Numbers to Omron PLC modules via CX Programmer, does it only affect the memory addresses that these modules will use?
Also, how much leeway do I have in having modules share Unit Numbers? I was under the impression that each module has to have a unique Unit Number, but some PLC backups I have browsed have the Analog and comms modules sharing the same Unit Number, like here: http://i.imgur.com/OhSgMLK.jpg.
Is this configuration possible because the I/O modules and comms modules use such vastly different areas of the PLC memory, that there is no risk of memory overlap even if Unit Numbers are shared?
Yet the Omron ETN21 manual says: "The unit number is used to identify individual CPU Bus Units when more than one CPU Bus Unit is mounted to the same PLC." - which implies the Unit Number must be unique.
I have a rather large set of Omron PLC's in use over several sites that I need to add Modbus TCP functionality to. While doing this, I am trying to minimize changes to the existing PLC code, but on some sites it looks like I may have to modify some of the Unit Numbers of the comms modules. I want to know how much freedom I have in doing this without breaking the existing functionality.
From reading the Omron manuals, it seems the only thing I have to look out for when changing Unit Numbers of existing modules is updating any related symbol or variable addressing to reflect the updated Unit Number. Does this sound correct?
Also, how much leeway do I have in having modules share Unit Numbers? I was under the impression that each module has to have a unique Unit Number, but some PLC backups I have browsed have the Analog and comms modules sharing the same Unit Number, like here: http://i.imgur.com/OhSgMLK.jpg.
Is this configuration possible because the I/O modules and comms modules use such vastly different areas of the PLC memory, that there is no risk of memory overlap even if Unit Numbers are shared?
Yet the Omron ETN21 manual says: "The unit number is used to identify individual CPU Bus Units when more than one CPU Bus Unit is mounted to the same PLC." - which implies the Unit Number must be unique.
I have a rather large set of Omron PLC's in use over several sites that I need to add Modbus TCP functionality to. While doing this, I am trying to minimize changes to the existing PLC code, but on some sites it looks like I may have to modify some of the Unit Numbers of the comms modules. I want to know how much freedom I have in doing this without breaking the existing functionality.
From reading the Omron manuals, it seems the only thing I have to look out for when changing Unit Numbers of existing modules is updating any related symbol or variable addressing to reflect the updated Unit Number. Does this sound correct?
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