RIO-8 Registers
Coils (0XXXX)
| DO1 | 1 | |
| DO2 | 2 | |
| DO3 | 3 | |
| DO4 | 4 |
Discrete Inputs (1XXXX)
| DI1 | 1 | |
| DI2 | 2 | |
| DI3 | 3 | |
| DI4 | 4 |
Input Registers (3XXXX)
None
Holding Registers (4XXXX)
| DI1Count | 1 | |
| DI2Count | 2 | |
| DI3Count | 3 | |
| DI4Count | 4 | |
| Debounce | in ms | 11 |
| BaudDiv | baud rate divisor | 21 |
| SerialMode | parity & stop bits | 22 |
| SerialTimeout | default=5 | 23 |
| RespDelay | in ms | 24 |
| QuietTime | in ms | 25 |
| MirSlaveTO | in s | 26 |
| MirMasterTO | in ms | 27 |
| LEDControl | 0=off, 1=on | 31 |
| MirrorMode | 0=off, 1=slave, 2=master | 32 |
| MirRepeat | in s | 41 |
| MirTimeout | in s | 42 |
| MirFailSafe | bitmapped | 43 |
| MirDO1Addr | addr for DO1 | 44 |
| MirDO2Addr | addr for DO2 | 45 |
| MirDO3Addr | addr for DO3 | 46 |
| MirDO4Addr | addr for DO4 | 47 |
| MirDO1Port | port for DO-1 | 48 |
| MirDO2Port | port for DO-2 | 49 |
| MirDO3Port | port for DO-3 | 50 |
| MirDO4Port | port for DO-4 | 51 |
| MirDI1Addr | addr for DI-1 | 52 |
| MirDI2Addr | addr for DI-2 | 53 |
| MirDI3Addr | addr for DI-3 | 54 |
| MirDI4Addr | addr for DI-4 | 55 |
| MirDI1Port | port for DI-1 | 56 |
| MirDI2Port | port for DI-2 | 57 |
| MirDI3Port | port for DI-3 | 58 |
| MirDI4Port | port for DI-4 | 59 |
| Pulse1 | in ms | 61 |
| Pulse2 | in ms | 62 |
| Pulse3 | in ms | 63 |
| Pulse4 | in ms | 64 |
| BCastReset | see below | 71-73 |
| Address | 74 | |
| DI1LongCount | 81-82 | |
| DI2LongCount | 83-84 | |
| DI3LongCount | 85-86 | |
| DI4LongCount | 87-88 | |
| SerialNum | 91-92 | |
| RadioSNum | radio serial number | 93-94 |
| LastCalTimestamp | Unix format | 101-102 |
| CalInitials | 103-104 | |
| LastUpdateTimestamp | Unix format | 105-106 |
Mirror Failsafe
Output failsafe levels are determined by the 8-bit value stored in holding register 43:
| Bits | Binary Values | Failsafe effect |
|---|---|---|
| 4, 0 | 00 10 11 |
DO-1 - no change DO-1 - OFF DO-1 - ON |
| 5, 1 | 00 10 11 |
DO-2 - no change DO-2 - OFF DO-2 - ON |
| 6, 2 | 00 10 11 |
DO-3 - no change DO-3 - OFF DO-3 - ON |
| 7, 3 | 00 10 11 |
DO-4 - no change DO-4 - OFF DO-4 - ON |
Broadcast Reset
The Modbus 
address of a RIO-8 device can be changed by broadcasting (i.e. sending to Modbus address 0) a write to holding registers 71-73.
The write should be done with a single, Write Multiple Registers command. In the first two registers (most signifigant word followed by least signifigant word), you should write the device's serial number. In the last register, you should write the new Modbus address.
As per the Modbus standard, the RIO device will not respond to this broadcast. Immediately after receipt, the RIO device will begin responding to requests made of the new address, however, this change will only be permanent if the DIP switches have all been set the same direction.
