PV C400 MicroLogix 1500 Data Access Error

[mtw12308]

Hi all.

I am working on converting a PV300 to a PV C400. System is using a Micrologix 1500LRP with several expansion IO modules. Communication is RS232 DH485 with two AIC+ modules. Cable connecting C400 to AIC+ is a 1761CBL.

Here's my issue. I have communication between controller and C400. I can read and write all I/O's that are native to the 1500LRP (I:0/1, O:0/3, etc). I can also read and write all bits, integers, etc. I can NOT read or write anything to or from the expansion modules (I:1/1, O:2/3, etc). I have my tags addressed as shown above. I can't seem to find any information on this other than this description from the manual which isn't really helping me.

"Communications - Data Access Error for Alias /*S:0 Param2*/, Controller/*S:0 Param3*/, Address is /*S:0 Param4*/, Communication Flag is /*:0 Param1*/

The terminal is having trouble reading the external tag at this controller and address.

Is the address configured in the controller? If so, make sure all addresses of external tags to this controller are configured at the controller. If one address is outside of the range, a block of addresses might show this condition. If the address is configured as write only at the controller, this address cannot be read. Set this external tag as write only and remove panel devices from your application that want to display this external tag."

 

[CeeDee]

Now, I've never had your problem before with that particular setup and I'm not expert by any means, so I'm kind of throwing out random ideas here.

using a Micrologix 1500LRP with several expansion IO modules.

Are you using an I/O bank?
Here are some things I saw in the manual.

"A maximum of one 1769 Expansion Cable can be used in a
MicroLogix 1500 system, allowing for two banks of I/O modules (one
connected directly to the controller, and the other connected via the
cable)."

"A maximum of either 8 or 16 expansion
I/O modules can be used, depending upon your system. See System
Requirements for Using Expansion Modules on page 1-7."

Do you have an end cap after the group of I/O modules attached to the controller?
"The end cap terminator is not provided
with the base or processor units. It is required when using expansion
I/O."

...Just some ideas.

 

[mtw12308]

The controller and program have been running fine with the PV300, so I don't suspect it is an issue with the setup of the controller or expansion modules. I've also tried it on two different controllers (1500LRP's) and have the same issue. Both controllers have the end cap on them.

Thanks for the suggestions! Any other ideas?

 

[rdrast]

Copy the actual I/O tags to an address in the N file, and see if you can access that.

 

[mtw12308]

Thanks rd! Pretty certain this will work since I haven't had any issues with reading/writing bits or integers. I was hoping to avoid having to copy them over for simplicity of conversion, but it appears this is not possible with the 1500 and C400.

 

[rdrast]

I can never remember exactly which, but I know that many comms drivers had issues with directly reading the I and O areas on SLC's and Micrologix, so I just always buffer them.

Saves headaches in the long run, doubly so when an input or output goes bad, and you re-assign it... No need to change the HMI program.