ML1200 to DH485 to EzTouch

[nhicks]

I have attached a DWG of a proposal I have sent to a customer.
The touch screen will be in the engineering control room. The local panel will be on the generator. The touch screen will have the option of locking out the switches on the local panel. Touch screen will have a switch to allow the local to be on control or not. When the touch screen turns Switches on, the lights need to correspond on the local panel, and vice versa, when the local is in control, the lights need to show up on the touch screen. I think most of this is pretty basic and doable.
I have just never dealt with 1761-NET-AIC or Data Highway before.

Any comments or suggestions would be great!

Thanks

 

[Lancie1]

I could not read the drawing with AutoCAD 2000. Is it a newer version?

 

[nhicks]

Its in either 08 or 04 format.
I will save it to PDF and report tomorrow.

 

[Mickey]

Here:
I used this to open it, its free
http://www.solidworks.com/pages/programs/eDrawings/e2_downloadcheck.html

 

[cjh]

Are you sure that the Multitek device can talk DH485? I couldn't find much about it on the internet but what I did find, didn't indicate to me that it could.
I hope that you are not thinking that you can talk both Modbus and DH485 concurrently on that port on the ML1200.

 

[nhicks]

Cjh - that was the intent/hope! The Multitek M802MD does put out Modbus RS485.

I thought the idea of the 1761-NET-AIC, would take RS485 modbus input and "convert" it over to a DH485 protocol? The same with the EzTouch - its puts out a serial RS485 doesnt it?

The easy fix for that, if it cant be done through the NET-AIC, is a dual com port ML1200 - although it would be nice to have that port open for monitoring. If I move the DMM to the second port - Is it possible to use the serial port on the NET-AIC to monitor/talk to the plc with logix?

Thans
NH

 

[nhicks]

Thanks Mickey!

 

[cjh]

One of the ports is a 'fixed' port. The other is adjustable for different protocols.

There are 2 questions:
1.) Can the fixed port do DH485 protocol? I don't know the answer to that one. I have a ML1200 but I won't be able to test that today. Maybe someone else can chime in on that one.
2.) What are the communications capabilities of your "Local Operator Interface"?
If it can do only DF1, then I don't believe that you can have all of those devices communicating to the PLC.
If the fixed port on the ML1200 can do DH485, then you could have another EZ touch or some other DH485 capable operator interface communicating locally as well as the remote touch screen on that port via AIC+s. And then you could connect your DMM to the other adjustable comm. port on the 1200.

 

[nhicks]

The Com 0 port on the front can do DH485. I beleive the second COM 1 port on the side will only do serial DF1? Not quiet sure.

The loval Op Interface are simple lights & switches hardwired to teh PLC's I/O. We need to stay away from the HMI on the local side, as the DMM provides all the digital metering. Going to two touchscreens, means we need to add a transducer for the information, and we are back at square 1.

I appreciate the help so far.

 

[Tom Jenkins]

nhicks is partially correct - CH0 will do DH-485, Modbus RTU, or DF1 protocols The other port (prog/HMI) is fixed and will only handle the default DF1 protocol and settings.

The AIC+ is essentially an RS-232/485 converter, optimized for the some non-standard timing and electrical considerations associated with Allen Bradley. You shouldn't try to use it as a generic converter.

The AIC+ does NOT convert protocol. You can't use it to convert DH-485 protocol to Modbus RTU protocol.

Finally, don't confuse RS-485 with DH-485. RS-485 is a standard for wiring, voltage, communictions control, etc. that will support any protocol that passes through it. DH-485 is a token ring peer to peer protocol, and proprietary to Allen Bradley, although it is widely available from others. In fact, the DH-485 messages from CH0 on the 1200 are carried on an RS-232 signal.

We have used EZ-Touch with DH-485 and multiple PLCs with AIC+ modules. Be aware, though, that you have to take precautions in your HMI messaging. If you have too much traffic on DH-485 you will quickly bring it down with multiple crashes.

 

[nhicks]

So can I take the Modbus DMM into CH0, and the AIC+ into COM1 via the DF1 serial cable?

 

[Tom Jenkins]

No.

You can set up CH0 for Modbus RTU, as either a master or a slave, and read the DMM.

The other port is exclusively DF1. If you are using it only for the EZ-Touch you are OK. I don't know enough about networking DF1 to comment on that, nor have I any experience using AIC+ with DF1. I'm sure others here can comment on that.

 

[nhicks]

Does anyone have any idea/experience with using the 1746-DPS1 DF1 Port splitter on a Micrologix 1200?
I wonder if I could use this to interface The DMM/Net-AIC?

 

[nhicks]

Can anyone point me to any ideas, or Modbut to DH485 converters other than the $1000 dollar PKV3500?

Thanks

 

[nhicks]

One other tidbit-
We have used the COM1 as the Modbus/RS485 in from the Multitek Meter. With the COM0 being DH485 capable - it should be able to communicate with the AIC+ shouldnt it - thus resolving the problem? We may loose a port for actually plugging in and monitoring, but thats minor.

Thanks
NH