Indigo 202 digital transmitters are designed for Modbus RTU (RS-485) communication. There are 2 groups of Modbus register addresses in use in Indigo 202: probe registers and Indigo registers. The probe registers are received from the connected probe, and are organized according to the probe's register map. Indigo registers include transmitter-specific information.
Received Modbus requests for register operations are treated in two different ways depending on the register address. Addresses above DFFFhex (that is, Indigo registers) are handled as normal requests. Lower addresses (that is, probe registers 0000hex ... DFFFhex) are passed to the measurement probe, and the response from the probe is again passed to original Modbus client. Indigo can also have a cache for commonly requested registers (Measurement registers).
The maximum response delay is 2 seconds (when data content needs to be fetched from the probe). The minimum delay between requests is 10 ms.
| For more details on the information relayed within Indigo 202 (transmitter-specific) Modbus registers, see Indigo 202 Digital Transmitter User Guide. |
| Address | Name | Data Type |
|---|---|---|
| Probe registers (according to the connected probe's register map) 1 | ||
| 0000hex | First measurement probe address | |
| DFFFhex | Last measurement probe address | |
| Indigo registers | ||
| E000hex | Status | 16-bit |
| E001hex | Notification and error bits | 16-bit |
| E002hex | Connected probe | text [30] |
| E011hex | Relay A status | enum |
| E012hex | Relay B status | enum |