CWT GFM A0A0161 - Modbus Register Reg [1; Modbus Serial Port Connections

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12.3 MODBUS REGISTER REG [1..10]
REG NO.
MNEMONIC
FORMAT
PARAMETER DESCRITION
1
GASFLOW
###
Gas flow rate
2
MAXLMT
###
Max Gas Flow Alarm Limit
3
MINLMT
###
Low Gas flow Alarm Limit
4
MINVOL
####
Low Volume Alarm (Not Enabled)
5
ACCVOL
####.#
Accumulated Gas Flow since last reset
6
RTCHR
#####
Total Gas Flow hours since last reset
7
RTCMIN:SEC
##.##
Total Minutes (MSB) and Seconds(LSB)
8
PKFLOW
###
Peak Gas flow rate for last Flow period
9
PKTIME
###.##
Peak Flow rate Time for last flow period
10
SPARE1
#####
Spare REG – Not used
12.4 MODBUS SERIAL PORT CONNECTIONS
To use the Modbus communications port the user must connect a suitable RS-485 driver and Modbus
host device to the GFM Auxiliary cable A3W0352. Connect the RS-485 driver output “A/( TxD-/RxD-)”
to the “BLUE” (Pin 7) wire. Connect the RS-485 driver output “B/( TxD+/RxD+) ” to the WHITE (Pin 1)
wire. Connect the RS-485 driver output “COM” to the “PINK” (Pin 6) wire. The RS-485 driver “COM”
should also be connected to the user supplied GFM Power Input common.
The following is the pin out for the GFM AUX Cable (P/N: A3W0352).
Pin No.
Wire Color
Function
1
WHITE
Modbus RS-485 B(TxD+/RxD+) serial port
2
BROWN
User supplied Power Input VIN+ (12-28 VDC @100 ma)
3
GREEN
CR-A - Will be active when gas flow is within programmed limits.
4
YELLOW
CR-B – Will be active when gas flow is within programmed limits.
5
GREY
User supply power common VCOM
6
PINK
Modbus RS485 and Vout analog common
7
BLUE
Modbus RS-485 A(TxD-/RxD-) serial port
8
RED
Gas Flow Analog output VOUT+ (0.00 – 2.55 vdc)