I need help accessing extended modbus services of a device. We are connected to a Smith Meter AccuLoad III. I can read from other registers, but I am confused by how to send commands through Ignition. Below is form the Accuload III modbus manual (page 394):
To use an extended service from Modbus, the following steps are required:
- Enter the command and any additional data required as specified for that command (the Extended Services
packet) into the buffer that starts at holding register 1 (functions 3, 6, and 16, register 1).
- Enter the length of the above packet in bytes into holding register 0.
- Enter the command to invoke the service by sending a Force Coil 4096 ON Command (function 5 or 15,
address 4096, data “on”).
- Retrieve the result of the service by reading the result packet in the extended service outbound buffer at
the start of the input register area (function 4, register 1). The number of bytes in the response packet is
located at register 0.