Campbell PVS5120 Series, Instruction Manual

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Appendix G. Generic Modbus® Control
G-2
TABLE G-2. Simplified Modbus® Control
CRBasic ModbusMaster()
Modbus Ctl Timed Ctl Pulse Ctl Coil Function Start Length
Start Start Start 00001 1 or 15 1 1
Serviced Serviced Serviced 00002 1 or 15 2 1
Auto Deploy Auto Deploy Auto Deploy 00003 1 or 15 3 1
Register
Bottles Bottles Bottles 40001 & 40002 3 or 16 1 1
SampPerBottle SampPerBottle SampPerBottle 40003 & 40004 3 or 16 3 1
NeverFull NeverFull NeverFull 40005 & 40006 3 or 16 5 1
PurgeTime1 StartHours PurgeTime1 40007 & 40008 3 or 16 7 1
LevelSetTime StartMins LevelSetTime 40009 & 40010 3 or 16 9 1
DepositTime StartSecs DepositTime 40011 & 40012 3 or 16 11 1
PurgeTime2 StartDay PurgeTime2 40013 & 40014 3 or 16 13 1
UsePurgeTime2 StartMonth UsePurgeTime2 40015 & 40016 3 or 16 15 1
SetTimeOut StartYear StartPulses 40017 & 40018 3 or 16 17 1
TimeOut IntHrs UseNegPulse 40019 & 40020 3 or 16 19 1
SamplerType IntMins TotalPulses 40021 & 40022 3 or 16 21 1
Bottle Bottle Bottle 40023 & 40024 3 23 1
Samples Samples Samples 40025 & 40026 3 25 1
Response Response Response 40027 & 40028 3 27 1
Batt Batt Batt 40029 & 40030 3 29 1
*Registers 40001 to 40030 contain 15 values encoded as IEEE 754, 4-byte floating point (CDAB)
Some Modbus® clients (masters) require the start address to be specified as
base 1 while others require as base 0. For base 1 devices, set your starting
address to the Register Number; for example, use a start of 23 when querying
Bottle . For base 0 devices, set your starting address to the Register Address;
for example, use a start of 22 when querying Bottle . Campbell Scientific
dataloggers require the start to be specified as the Register Number .
All values contained in the registers are IEEE 754, 4-byte floating point
numbers. This means that the values occupy two registers each, with each
register holding 2 bytes. Data is transmitted with a swapped word order. This
means that the low order word is transmitted on the wire first, followed by the
high order word. The words (
registers
) use a big endian architecture. A
common notation for this byte arrangement is “CDAB” where “CD” is the low-
order word and “AB” is the high-order word.
Modbus Packet Example 1: Set "Start" Coil = ON
TX: 01 05 00 00 FF 00 {CRC}
RX: 01 05 00 00 FF 00 {CRC}
Modbus Packet Example 2: Read "Start" Coil
TX: 01 01 00 00 00 01 {CRC}
RX: 01 01 01 01 {CRC}, if "Start" coil is true, bit 0 = 1
or
RX: 01 01 01 00 {CRC}, if "Start" coil is false, bit 0 = 0