2500 Modbus TCP (Ethernet) communications.
The 2500 Modbus TCP parameters are presented in a slightly non-standard manner. The notes below will assist in setting up the communications channel.

Introduction
The 2500 Modbus TCP slave communications channel provides up to 4 TCP sockets. This allows up to 4 external Modbus TCP Masters to communicate at the same time.
However please be aware that the hardware is actually an Ethernet to serial Modbus gateway and the serial line is limited to 38400 baud for the 2500 - so don't expect any more throughput than you would expect from that speed serial line.

Unit Ident
The 2500 expects the Modbus TCP Unit Ident field to match the 'Comms address' as set in the instrument. This is not strictly compliant with the Modbus TCP Specification for stand alone instruments but is in agreement with a gateway where several Modbus instruments may be attached to the serial line.

IP Addresses
IP Addresses are usually presented in the form "xxx.xxx.xxx.xxx" - where the xxx numbers are decimal values. Within the instrument each element of the IP Address is shown and configured separately. "IP address 1" relates to the first set of three digits, IP address 2 to the second set of three digits and so on. This format also applies to the subnet mask, default gateway and preferred master IP Address.

Default setup
By default the 2500 is set to a fixed IP address of 192.168.111.222 with a default subnet mask setting of 255.255.255.0.

MAC address
Each Ethernet module contains a unique MAC address, normally presented as a 12 digit hexadecimal number in the format "aa-bb-cc-dd-ee-ff". In iTools parameter explorer for the 2500, the MAC addresses are shown as 3 separate decimal values in the "Operator.COMMS" list. MACaddr1 shows the first two values... MACaddr3 shows values 5,6. To show these values in the standard format, they must be converted to hexadecimal.

For example: MACaddr1 = 10 (0x000A), MACaddr2 = 36096 (0x8D00), MACaddr3 = 456 (0x01C8) translates to 00-0A-8D-00-01-C8

DHCP Settings
You need to consult with your network administrator to determine if the IP Addresses for the instruments should be fixed or dynamically allocated by a DHCP server. If the IP Addresses are to be dynamically allocated then all MAC addresses must be supplied to the network administrator. NOTE: if the DIP switches are used to set the Instrument address, the DHCP setting is also controlled by the DIP switch.

Dynamic Addressing - If the 2500 is to use Dynamic addresses, the values of the IP address parameters will reflect the value allocated by the DHCP server and will be read-only. At start up the IP addresses will show a value of 0 until the DHCP server has supplied the appropriate information.

Fixed Addressing - For fixed IP Addresses the Network Administrator will provide the IP address as well as a subnet mask and Default Gateway (if necessary).

Setting the DHCP parameter to 'Fixed' will make the IP addresses writable and the values supplied by the network administrator may be entered.

Preferred Master
These parameters identify the IP address of a Master controller. This could be anything from a strategy engine to a simple setpoint broadcast. As such, it is important that this Master remains in communication with the 2500. To this end, one of the 4 TCP sockets is reserved for use by the Preferred Master, ensuring that high network traffic cannot lock it out.

Network Connection
Use standard CAT5 cable to connect to the Ethernet 10BaseT switch or hub. Use cross-over cable only if connecting one-to-one with a PC acting as network master.

Custom Linearization Tables
It should be noted that the 2500 cannot load Custom Linearization Tables via the Modbus TCP link - the Config port must be used.

The reason for this is historic: Cust Lin Tables have to be loaded using the Factory Communications mode and this is constrained to only work at address 255 at 9600 baud. Since the Ethernet daughter board communicates at 38400 baud and uses address 255 for internal housekeeping, it is incompatible with Factory Comms.