1761-net-eni

I am confused about the 1761-NET-ENI module. The website states that this module is not designed to act as a bridge connection. I need it to maintain a connection to READ ONLY some I/O and update a SCADA program as close to real-time as possible to also be uploaded to a website as close to real-time as possible. Can this module do this? What are my limitations?

I have used this module with the MicroLogix 1200 and 1500. It adapts the DF1 protocol port to Ethernet by wrapping the TCP/IP protocol around it. On the DF1 side it connects to ONLY 1 unit. When a packet arrives at the I/P address of the NET-ENI unit it routes it to the connected unit. If the Micrologix unit wishes to send messages to other units on a DF1 network it sends it in the normal way then the station number is translated by the NET-ENI using internal table to an I/P address. The NET-ENI then sends the message to the appropriate I/P address where something, possibly another NET-ENI unit, translates it back to DF1 for the receiving unit. It can't bridge between multiple DF1 devices and Ethernet. The module does have an email capability which I haven't used yet. The email would be triggered by messages from the MicroLogix unit. Any further interaction with the Internet would have to be done by the PC/SCADA package which is reading it. I hope this helps.

Okay, seeing as I am not connecting this net-eni to another PLC, only to a PC, are we saying my original question is really SCADA program dependent. I was assuming that any SCADA program would be restricted by the hardware it was attempting to communicate with.

I didn't think of the possibility of connecting an ENI directly to a PC even though the connection diagram shows that as a possibility. I guess you wouldn't loose any speed if all the rest of the connections are using the ENI also. It's just so much cheaper to get a PC on to Ethernet (like a $10 card) that I hadn't though of that. Note that the link will be as slow as the slowest serial port baud rate. If all the PLC's you are talking to do not have ENI's but have Ethernet as a regular capability (eg the SLC 5/05) then the ENI on the PC would be the bottleneck.

I am aware of the serial bottleneck. This PLC will not communicate with anything but a PC, and even then, the PC ONLY to READ I/O. All I want is get status on my I/O at any given time. I do have other PLCs (NON AB) that I will be doing this with, but each of them the same deal, a PC reading I/O. I do not believe that the serial bottleneck will be a major factor seeing as I am only READING some I/O. I only want to check to see if certain machine operations are occuring or not, but as close to real-time as possible.

'Reading I/O' is no faster than reading any other type of information from the PLC. But if you are saying the total amount is very limited then I understand what you are getting at.

I have used several NET-ENI modules, they work great....If you set up MSG instructions in your code, you can have them trigger the SMTP messages Bernie talks about....Works well, we don't have full SCADA here, so and email to the right person in the event of a critical alarm is handy....especially in utility aplications.

Greg