Note! : In this command reference guide where number 127 is called, there is only the first 125 used normally, do not use the rest of the two, they held for the manufacturer's diagnostic purposes!
TERMINOLOGY: DEVICE ID = selects the device to talk to. ADDR selects in which value to talk to within a device.
Address values are not the binary format (to get binary format decrement by one)
Read coil status: (Binary values. Functions supported: 1,5,15 decimal)
READ ONLY 1-1016: 127x8 bits of relay presence map
READ/WRITE 1101-1132: 32 bits of group status
READ/WRITE 1201-1327: 127 bits of analog value fetch triggers (write to 1 to trigger / read until 0 to check if fetch is complete)
READ/WRITE 2001-3015: 127x8 bits of relay status
READ ONLY 4001-4100: Interface ready status. Read any of these to see if device is ready. You only need to read one address as it is the same bit repeated for testing/convenience only.
1=ready 0=interface in startup scan mode
Holding registers: 16 bit values. Functions supported: 3,6,16 (decimal)
READ ONLY 1-127: Device type map Only the following four (high byte) mainly supported devices will be mapped in with their sub values (low byte):
First Device type high-byte followed by // the available access points, low byte:
1 = Relay cards // 4, 8, 16, 32, 48
2 = iDIM // 16
3 = System Groups // 32
4 = Digital photocells // 1=PCC-1; 3=PCC-3 only, not Analog/Digital!)
READ/WRITE 128-635: Dimmer level with 1 sec fade rate (must set fetch trigger to read back current value) (127 x 4 holding registers)
READ/WRITE 636-1143: Dimmer level with 3 sec fade rate (127 x 4 holding registers) (if read, mirrors the current dimmer levels)
When writing the fade rate one must makes sure that another device will not modify the fade rate before the dimmer level is written.
Fade rate should be written first then the dimmer level with consecutive packets to prevent another device changing the fade rate between these two packets.
This is not a problem if there is only one Modbus mastering device.
READ/WRITE 1144-1145: GLOBAL FADERATE 32 bit fade rate value in 1/60th sec steps. Hi-Lo order (1144 is bits 31..16) (1145 is bit 15..0)
The any GLOBAL, 1sec or 3sec fade rate type dimmer accessing methods override the last fade rate of the affected dimmers.
READ/WRITE 1146-1653: Dimmer level with GLOBAL FADERATE (set global fade rate first at address 1144 and 1145) (127 x 4 holding registers) (read only mirrors the current dimmer levels)
READ/WRITE 1654-3177: Dimmer and Fade Rate continuous access. 3 x 4 x 127
Use this area to access dimmer values followed with an immediate 32 bit fade rate value.
This should be used if the ModBus-to-GR2400 interface is accessed by multiple Modbus masters.
This area allows for dimmer values and fade rates be accessed with one communication packet.
This prevents the possibility of another node modifying the fade rate before the dimmer level is set
(read returns the last read current dimmer levels and the last written fade rate)
READ ONLY 3178-3685: Read analog input value. These values only get fetched and updated if the corresponding analog value fetch triggers are set. (1201-1327)
WRITE ONLY 3687: Modbus ID change register. Only function 6 is supported.
WRITE ONLY 3688: Unlock Modbus ID change.
Changing the Modbus ID:
To prevent unintentional change to the Modbus ID of the interface the following sequence must be done in order to change the ID.
1. Write 0xa354 (hex) to the Unlock Modbus ID holding register.
2. Within one second take the new Modbus id value and add 0x5500 (hex) to it.
That value must then be written to the Modbus ID change register (3887).
For instance if you would like to change the Modbus ID to 57 decimal then:
First one would write 0xa354 (hex) to holding register 3688 then write 0x5539 (hex) to holding register 3687.
READ ONLY 4001-4100: Interface ready status. Read any of these to see if device is ready. You only need to read one address as it is the same value repeated for testing/convenience only.
1=ready 0=interface in startup scan mode