AB PLC, MODEM , MODBUS Connectivity

Can any one suggest a AB PLC for the below requirement:
Digital Input: 38
Analog input: 19

This PLC will be connected to a DCS via an Industrial modem.
Protocol being used by DCS is Modbus. SO the PLC should be Modbus Slave.

Also the PLC will gather data from a flowmeter locally via modbus. So the PLC should act as a Modbus Master and flowmeter as Modbus slave.
The information from the flowmeter will also be given to the remote DCS via modem.

I thought about prosoft. But they have two products and i donot know which one to use. 1. 3100-MCM (Modbus master/Slave comm)
2. MVI46-MCM (modbus master/slave comm)

As i am familiar only with AB PLC i wanted to use that PLC only. I understand that only SLC 500 will be economical option (is there any other economical options available)

So any suggestion would be of great help.

Many thanks

[Mickey Mills]

MicroLogix might do it. Also check out www.protocolconverter.com

Mickey

The MicroLogix 1200 and 1500 have Modbus RTU Slave options, but no Modbus RTU Master. Besides, getting 19 channels of analog input even into a MicroLogix 1500 is pushing it.

I'd use a regular old SLC-5/03 and the Prosoft MVI46-MCM module. Select your I/O as needed... you say you're using SLC because it's familiar to you.

The MVI46 is a newer version of Modbus module than the 3150 series module, so I'd select that. It has two ports that can be Modbus Master or Modbus Slave, so your programming will be similar for both Modbus channels.

Thanks for your info.

One more thing which i wanted to say is:
The PLC does not control(No logic) it just gathers Digital input and Analog input Plus Flowmeter data via modbus and pass it to a remote DCS via modem. As i am familiar with AB i thougt of doing this with AB. But is there any other option with which i can avoid AB PLC and do the above job economically.

Many thanks.

[Jim Dungar]

Have you considered using I/O modules only without any PLC?

ALERT ALERT - possible product promotion

Look at the Schneider Electric line of Momentum I/O modules (http://www.modicon.com/Default.htm) and a Modbus serial communications adapter from Niobrara Research and Develeopment (http://www.niobrara.com/mst_cut.html). Your Modbus data aquitition device should be able to get the data direct from the input modules.

[Ken Roach]

Oh, gosh, the SLC is way overkill for this application if there's no local control (and won't be in the future). The only glitch you really have is that an I/O only product won't have a secondary master channel to poll data from your flowmeter.

If you use "dumb" RTU I/O you'll need to have the master DCS poll both the I/O blocks and the flowmeter separately.

Momentum I/O is probably the best-known for Modbus slave connectivity. If you're enthusiastic about using A-B hardware you can get a FLEX I/O adapter for RS-485 Modbus from Prosoft.

Can any one suggest a AB PLC for the below requirement:
Digital Input: 12 ，Output: 16
Analog input: 4

any questions may be of help

many thanks

Rich,

If you are not 'locked' into AB, take a look @ Control Microsystems web site.
I'm an 'ole' AB user, but in recent years C/M's products take up less 'real estate' & I havn't had a hardware problem yet. The Chicago Water Dept. uses over 500 of them as their RTU's.

Anyway, just food for thought.

[Mickey]

DaMan,
You are the only other person I have seen talk about CM stuff, besides myself.
I am a big,big fan of ControlMicrosystems SCADAPacks PLC's. I have been using them for the past 3 or 4 years ( no problems )

Jim Dungar,
You would like them to, the programming software ( instructions) is very similar to Modicon