Host Engineering Forum
General Category => MB-GATEWAY => Topic started by: b_carlton on June 14, 2011, 05:03:17 PM
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Let's say I had multiple Gateways (each eith its own I/P) each attached to multiple RTU units.
Now I wish to send information to a specific RTU unit at a specific gateway using a H0-ECOM100.
As far as I understand the Modbus RTU ID gets translated to a specific I/P in the ECOM100. Would I, for all the RTUs attached to a single Gateway equate their RTU IDs to the same I/P as the Gateway? Even though a message is sent to the same I/P the RTU ID must be included in the message also.
[Edit: I think I see the confirmation of my guess on page 6-6 of the ECOM manual under the note about Modbus/TCP to Modbus/RTU convertors.]
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Each "logical" Unit ID configured in the ECOM100 has
1. IP Address
2. TCP Port number (502 is Modbus/TCP)
3. (RTU) ID
This 3rd Modbus/TCP parm is normally 255 or 1 for Modbus/TCP devices, but for any Modbus/TCP->RTU Gateway, you would set it to the RTU Unit ID off the gateway with THAT IP address. Obviously, this is how you would use the ECOM100 with our latest MB-GATEWAY product.
As an aside, for the 275e MX Controller, the IP Address, TCP Port Number, and (RTU) ID are just parameters in the MRX/MWX instructions. The 275 CPU is still in development, and is part of the MX Controller and DirectSOFT/MX products that are currently in Beta release.