Bem331 configuration

I'm an A-B guy but occasionally get pulled to work on GE. I'm trying to add a new analog input to an existing analog card connected to a 90-30 via a BEM331. When I look at the hardware config in the BEM331 I can't begin to understand what it does. I've tried using a known I/O point as a starting point...but that hasn't gotten me far. The point where it's mentioned in the BEM331 config (in VersaPro) doesn't seem to match up with it's physical connection point.


Any help to get me point in some direction would be much appreciated!!

Thanks!!
View attachment BEM331.pdf

The BEM331 is a Genius bus controller. Genius is GE's old remote I/O network. The analog input module is part of a network drop.

In the fragment of the hardware configuration screen for the BEM331 you've posted, the left hand column is the network drop number. For drop number 8, the BEM331 is configured to expect to see 16 bits of discrete data (that's the 16 in the fourth column) and 8 channels of analog data from drop number 8 (that's the 8 in the sixth column).

It passes the 16 bits of discrete data it receives from drop 8 to PLC input addresses %I0033 - %I0048 (third column). It passes the 8 channels of analog data it receives from drop 8 to PLC analog input addresses %AI0057 - %AI0066 (fifth column).

Those 8 channels of analog input data could be from a single 8 - channel analog input module or they could be from two 4 - channel modules. Neither the BEM331 nor the PLC care. All they care about the fact that they're getting 8 16-bit integers and that they should copy that data to 8 consecutive channels of %AI memory.

Network drops 5, 6 and 7 have no discrete data so you can ignore the %I address for those drops. For each of those drops the BEM331 is configured to expect 8 channels of analog input data. It copies the 8 channels from drop 5 to PLC memory %AI0033 - %AI0040, the 8 channels from drop 6 to PLC memory %AI0041 - %AI0048, and the 8 channels from drop 7 to PLC memory %AI0049 - %AI0056.

Drops 9 and 10 have no input data configured.

You didn't say what the analog input module is connected to. There will also be hardware configuration required for that end of the network, but if all you're doing is to wire a new sensor to an existing module you probably won't have to make any changes to it. I say "probably", because it is possible that the unused channels are disabled. Provide more details and I can point out what you will need to look for.

First - thanks for your awesome explanation, Steve! I greatly appreciate your time.

Attached to the Genius bus is an 8 slot (it says 'slot' but I would prefer 'channel') current source analog input 003R04, a 16 slot 120VAC grouped input 008R03, a 16 slot 12-120VAC grouped output 015R04, and a terminal base with no module.

I'm connecting two 4 - 20 signals to the analog card from flow indicator transmitters; one was existing (but some new electronics on the field side) and one is new (same as the new electronics in the first one).

The existing one (with new 'stuff') seems to display correctly so I'm using that as a reference.

The existing FIT connection is landed on the far right of the analog module which is labeled '1' on the slot on the module (I don't have a photo of the terminal blocks to be sure that they're not numbered opposite...I don't think that they would be). The existing FIT is linked to %AI0057. What would the corresponding addresses be for the other seven physical channels on the analog card? Or do I have to make a change to the mapping of the Genius bus in the hardware config to 'create' that link?

Again - thank you!!

I think that I'm good on this - it seems to make sense. I've got 8 bytes of analog data coming in beginning with %AI0057. My existing device is landed on the first channel and it tied to %AI0057 so my third physical device would translate to %AI0059. I will check this in the field.

Thanks, Steve!