a device send DO thu its Modbus, can I connect to Micrologix and read that data ?

[leonlai]

a device send Digital Output through its Modbus
Can I hook the Micrologix 1400 to that device through the Modbus (serial cable) and get the DO from the device ??

Thanks

[bernie_carlton]

Let's clarify what you are saying first.

a device send Digital Output through its Modbus

Which is this ...

1. A device which will control Digital Outputs and can receive the command through Modbus from a Master device.

2. A device which receives Digital Inputs but can be read by a Master device using Modbus.

3. A device which recieves Digital Inputs then sends their status using Modbus as a Master to a Slave device?

4. A device which sends commands as a Master to a Slave device using the Slave as its outputs.


The 1400 can be set to be the Master in 1 and 2 or the Slave in 3 and 4 but not all at once.

If this is all confusing at least provide the maker and model number of the device.

[leonlai]

This Device supports ASCII transmission modes thru Modbus Protocol
AND this device operate as slaves to other Modbus devices !

So, you mean I can connect them together and read the data from the device right ??

The second thing is I never do this before so what command or what steps should I do to make Micrologix regconize the device and read its data !!

Thanks

[leonlai]

btw, I use RSLogix 500

[bernie_carlton]

Edit: I missed that you said ASCII transmission. The Mirologix supports RTU transmission. See if the device can be switched to RTU. Otherwise everything I have said below is out the window. Sorry



1. You will set the serial port on the Micrologix as a Modbus Master. Note: by doing this you won't be able to use the serial port for programming but you are probably using the Ethernet port anyway.

2. You did not define if you are using RS232 or RS485 (RS485 is more common). Either way you will need to use the proper cable attachments.

3. You will use message (MSG) commands in your program which define the Modbus addresses in the slave, number of words, and the destination registers (usually N registers) in the Micrologix for the information.

This piece of information from AB shows how to use a Micrologix 1500 to a Powerflex drive but the ideas on messaging apply almost directly (except for the Modbus address) and other sections give good information.

You won't need the NET-AIC if you are using RS485. The Micrologix 1400 already has that. You'll just need a wire breakout (1763-NC01)

[leonlai]

InsiteIG model 4000 which is the device I use to be slave with Micrologix 1400, Its has an auxiliary port (using both ASCII and RTU)and the maintainance port (DB9 serical cable to Laptop) (only ASCII) !

Do you think If I can find out a auxilary to serial dapter, I able to connect the device (auxilary port) to PLC (Serial port), I can read information from the device ??

I use Ethernet to connect PLC and HMI by a modem !

[bernie_carlton]

The data sheet and manual don't give enough information on the electrical specifications of the Auxiliary port. You'll have to get with them for information and advice on a connection.

Otherwise the last section of the manual gives a good overview of the Modbus addresses and which can be accessed through the serial port.

If you can set up an RS232 or RS485 connection to the Auxiliary port you should be good.