The problem is I need to interface with 35 Modbus Slave devices (Tyco NGC-20) to a DCS system (Provox-IDI). The DCS system can interface with modbus devices but every Modbus register takes a virtual I/O. The problem is that the slave devices report all read registers in static blocks of 70 registers and write registers in static blocks of 120 registers. Therefore I would need (35 x (70 + 120))= 6650 virtual I/O, in fact only 35 process values and 35 setpoint are needed from the total of 6650.

I am looking for a configurable device e.g. a gateway that acts as a Modbus RTU master to collect only those registers that are needed on one side and remaps those in a compact table and puts this table back on Modbus as a slave device on the other side.

 

How about a PLC with two serial ports? -- the first configured as a modbus/rtu master over RS-485 (multidrop), and the other port as a modbus/rtu slave? I can think of many brands that could do this.

 

As "scadametrics" said, it sounds like what you want is a PLC with both master and slave Modbus/RTU ports.

 

Yes, I agree that a PLC as described will do the job. But it sounds like an overkill situation to me. There must be a much simpler and cheaper solution on the market that suffices for this application.

 

We make two different gateways that would work for such an application (depending on your combination requirements of Modbus/TCP and/or RS-485 based Modbus RTU).

The XLTR-1000 is a 2-port RS-485 device, so you can set up one port to be a Modbus RTU master and the other port to be a Modbus RTU slave.
<i>http://iccdesigns.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=ICC&Product_Code=xltr1000</i>

The ETH-1000 has an Ethernet port and and RS-485 port. The Ethernet port can act as a Modbus/TCP client and server (simultaneously, even), while the RS-485 port can act as a Modbus RTU master or slave.
<i>http://iccdesigns.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=ICC&Product_Code=eth1000</i>

For both gateways, register assignments are completely user-configurable, so you can remap any register on any remote slave/server device to exist where ever you want it.

Regards,
Darrin Hansen
ICC, Inc.

 

Rogue Engineering also makes a Gateway device that could be easily customized to do what you want. It has up to 4 RS232/RS485 serial ports, each of which can speak a different protocol or have a different register mapping if so desired. Here is a link to the product cutsheet.

https://www.rogue-engr.com/cportal/images/cutsheets/gateway_cutsheet.pdf

 

Supposedly Red Lion HMI units (and their DIN rail mount processor box) can have multiple simultaneous protocols and even do data conversion (programmable) between the two protocols. I might be using one with a new robot project to provide data exchange using generic TCP/IP and some custom written software in both the HMI and robot. They have free programming software download and prices seem reasonable.

KEJR