We (FieldServer) have done the integration from Wonderware to Speedtronic MKIV successfully using our communication bridge, the communication bridge
is essentially a black box which we load different protocols into it, in this case GE Speedtronic MKIV and Modbus TCP/IP and the points are then mapped through from GE Speedtronic to Wonderware. This application worked well.
Several companies ahve products that would suit your needs. Both CSE engineering and Control system technolgies have HMI products for the MK-4 that support modbus. I believe both have products that can support modbus directly to the panel.
PRISM systems has an OPC server that we are using for native data collection from MK-4 to wonderware historian - it is for use on the MK-4's that are on arcnet - it is only one-way though but well suited for a historian.
CSE Engineering, Inc. does have a gateway solution which communicates to the Mk IV in its native communication protocol and can provide full bi-directional communications in many protocol formats. IE: OPC, Modbus (Serial and TCP/IP), All FANUC protocols, All Allen-Bradley protocols, Siemens, Bailey, Westinghouse, etc.
If you wish further information please contact Svitlana Palona at +1 - 925-686-6733.