Read/Write a bit in a Modbus Address

[Ollie]

Greetings,
I'm working on a project for a customer of mine. I'm working off of his I/O mapping list. We are using MODBUS to communicate to a Motorola MOSCAD FIU. According to the I/O Map, I need to read a bit from address 307682:01 which normal I would translate into 307682.1 but Lookout is not excepting this address as a valid Data Member. So I did some troubleshooting of my own and found that Modbus Data member (307682) is only used as "a 6-digit addresses of 16 bit input registers encoded as unsigned binary integers ranging from 0 - 65535." I guess an analog value.

Is my thought process correct on this? Does my customer need to change his I/O mapping. Am I overlooking something?

Attached is a copy of the I/
O map.
Oliver Scheurer
Aegis Solutions, Inc.
2660-T Yonkers Road
Raleigh, NC 27604
Phone: (919) 861-0103 Ext. 231
Fax: (919) 861-0104
www.aegis-solutions.com

[Ollie]

WOW!!.. I get to answer my own question. You all are slow... J/K...

Anyway, the fine people at NI Tech Support Helped me out with this one. Seems that it is a problem related to Lookout and Modbus. After discussing this problem with a few engineers, I decided to call the customer and let him know of his mistake. Well, he proceeded to tell me that "Wonderware can do it with out a problem". So I called NI Support again, and they told me that further research showed that it is something that was not put into Lookout. The Support engineer started a "CARD?". But he also gave me a work around.

1. create an expression
2, enter getbit(3,1)

This expression will return a ON status since the number 3 in binary is 1 1 and looking at the first bit is 1.

So for my
application I would use
getbit(modbus1.307682,1)

I hope this makes sense.

Oliver Scheurer
Aegis Solutions, Inc.
2660-T Yonkers Road
Raleigh, NC 27604
Phone: (919) 861-0103 Ext. 231
Fax: (919) 861-0104
www.aegis-solutions.com