Connecting Multiple NT11's to one PLC

I am trying to connect two NT11 Omron HMI Interfaces on to one PLC.
Using a CIF11 RS422 adapter gives me the ability to wire 4 wires (RDA, RDB, SDA and SDB) to the first unit. Then I paralleled off the first unit to the second.
This doesn't work as I hoped, I even trying changing the HMI from Host to NT 1:1 link with no luck.
Is there a simple way to connect 2 NT11's onto one PLC.
The second NT11 is for display purposes only and will be mounted in an XP enclosure.

Been somewhere in the order of eighteen years since I've messed with this, but I do recall that you need 'NT Link 1:N'. This needs to be set at both the PLC and each HMI.

It gets kinda fuzzy after that, though.

It may also help if you say which PLC you're using, as well. More complete questions usually get more complete answers.

I am assuming that since you mentioned an xp enclosure, you mean explosion proof enclosure and if so, I have several questions.

1. do you mean the display itself will be mounted on the panel door or inside an enclosure with a see through window?
if mounted in the panel door, does the system meet your hazardous environment ratings?
can the display be pressurized or purged without damage?
if the display is inside the enclosure, does your window meet your hazardous environment ratings? NOTE, plexiglass will not meet the requirements!!

2. your enclosure must be purged / pressurized per nfpa 496.
3. the power to the enclosure and communications cable must be run in rigid conduit and have seal offs at the required location(s)

regards,
james

To answer the questions:
Its a CJ1M CPU11 PLC that we are using.
The display is mounted inside the explosion proof enclosure with a glass window to view it. All connections to the box are sealed