MODBUS RTU into MICROLOGIX 1200 2 port

I have 4 registers that I am attempting to bring into my PLC. Okay here is my hardware. A Right Smart 2400 with a 2 wire RS485 which I have wired to a Blackbox RS-485/RS-232 converter which is connected to my 1200 with a regular PM02 cable. First of all my goal is to read this data not to write anything back to the RTU. Second, The RTU is currently configured to be the Master and I have set the 1200 to be the slave. I am attempting to get the MSG in RSLogix 500 set-up but am unsure of too many things and all of them have to be exaclty right. The data is 16 bit but can I bring in Floating intergers? Does anyone have any good instructions for a Modbus idiot?

The MASTER unit is the one which does all the work. If the 1200 is a slave then all it has to do is have the port ready to receive MODBUS queries. It will not have any MSG commands.

Thanks Bernie that is good to know. Now, in my CH 0 config I will not be using the coils or contacts but is the holding register where the RTU will send data. N13:0 thru N13:3 (for my 4 registers). This is very unclear since I was given the registers from the RTU programmer of 8193, 8194, 8195, 8196. How does this come into the N13:? Also in Protocol control is "No handshaking" the correct setting for this?

The RTU programmer might have to change the Modbus register addresses he is requesting.

The MicroLogix 1200's Modbus implementation always starts at Register 1, which is fine for 95% of the applications you'll run across. The usual Modbus data file is the ordinary SLC data file size of up to 255 Words. You can use the Extended file capability to span the Modbus data file space across 5 more MicroLogix data files for a total of 1536 Modbus words.

Since your RTU programmer started the registers at 8193 (which is 0x2001 hex), it's out of range of what the MicroLogix 1200 can have addressed.

To my knowledge there's no way to offset the Modbus address space in a MicroLogix 1100/1200/1400/1500 controller from starting at 1.

I now have a solution since there is no way to offset these registers within the Micrologix. A standalone Modbus module has to be purchased and programmed accordingly. Pro-Soft offers many different models but the one that will fill my need is a 4-port model #5102-MCM4-DFCM4. Each of these ports can be configured RS-485 or DF1 (RS-232). Anybody bought one of these before? I may be jumping the gun but this "SHOULD" take care of the issue.

I found a Modbus RTU to DF1 gateway device made by Exemys in Argentina that will emulate up to 32 N-files in a DF1 device as Modbus RTU addresses that start at 40192.

http://exemys.com.ar/beta/english/products/converters/SGW1-MB-DF1/index.shtml

The last N-file would cover Modbus addresses 8128 to 8383.

I haven't used this device but it seemd to be simpler (and probably less expensive) than the full Prosoft solution. The Prosoft device is the zero-risk decision.