AMC-400 Series Digital Transmitter with Smart Sensor 2
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APPENDIX: MODBUS REGISTER MAP
A developer of a monitor can use the below MODBUS register map to query gas type and gas
concentration from an AMC-400 series digital transmitter. A minimalistic monitor need only poll
a couple of MODBUS registers to achieve the gas concentration.
Setup polling MODBUS address with MODBUS protocol at 9600Baud, Even Parity on
EIA/TIA-485 link. Please see section 3.2 FRONT LID OVERVIEW for MODBUS
address. The MODBUS address can be configured from the transmitter with the user
interface. Please see section 5.2 INITIAL CONFIGURATION for details.
Only Read Holding Register(s) MODBUS function(s) can be used to read these
register(s). Up to a maximum number of 12 registers can be read at a time.
Poll Transmitter Status (Register 2)
o
A hex value not equal to 00xx indicate not available or not ready.
o
A value of 0x008F indicates transmitter is okay at 9600baud with no analog
output available.
Read Gas Number/Device Address (Register 3)
o
A hex Gas Number of 00xx or 01xx or 02xx or 03xx or 09xx represents CO, NO
2,
CH4, Pro(C3H8) or H2 respectively.
Read Sensor Unit 32 bit Registers r28-r29 currently in PPM or LEL.
o
Swap 16bit values to create 32bit IEEE754 float value in PPM or LEL.
Notes:
*1 Read. These registers can be read or written, write operation is not currently supported and
will produce unpredictable results.
*2 Not Supported. The transmitter will provide default or unspecified value.
*3 Float. These registers are a IEEE754 decimal 32 format floating point representation when
low and high 16bit registers are swapped (I.e. IEEE 754 Sensor Unit float = r29[31:16] and
r28[15:0]). Holding Registers (MODBUS function=03) is supported.
The registers below are based at address 0 and the maximum consecutive registers
