GHM Delta OHM PMBsense-A, Operating Manual

Page: 9 / 26

PMsense
- 9 -
V1.0
5 PROPRIETARY PROTOCOL
To use the proprietary protocol, it is necessary to connect the instrument to the PC via
a RS485/USB (e.g. RS51K) or RS485/RS232 converter and use a standard serial
communication program. In the serial communication program, set the COM port
number to which the instrument is connected and the communication parameters as
follows:
•
If the MODBUS-RTU protocol is set as the operating protocol in the instrument
(default), set the Baud Rate 57600 and the parameters 8N2 in the serial commu-
nication program, then power cycle the instrument and send the command
@
within 10 seconds from the instrument power on.
•
If the proprietary protocol is already set as the operating protocol in the instru-
ment, it is possible to operate with Baud Rate 57600 and parameters 8N2 by
sending the command
@ within 10 seconds from the instrument power on, or
you can let the 10 seconds pass without sending the command @ and operate
with the communication parameters set in the instrument (default 19200, 8E1).
To change the instrument configuration, the serial command CAL USER ON must be
sent first (the instrument replies with USER CAL MODE ON). The command CAL USER ON
is automatically disabled after a few minutes of inactivity. If the settings should be only
read, the command CAL USER ON is not required.
Below is the list of the serial commands.
Instrument information:
Command Reply Description
G0 Model Instrument model
G1 & Revision | Instrument hardware revision
G2 SN=nnnnnnnn Instrument serial number
G3 Firm.Ver.=x.y Instrument firmware revision
G4 Firm.Date=yyyy/mm/dd Date of firmware revision
GC Fact.Calib.Date= yyyy/mm/dd
User.Calib.Date= yyyy/mm/dd
Cal.Mode=
Factory or User
Date of factory calibration
Date of user calibration (CO
2
only)
Type of calibration active (CO
2
only)
Protocol:
Command Reply Description
@ &| Keeps the proprietary protocol operational even after 10
seconds from instrument power on. It must be sent within
10 seconds from instrument power on.
DPn &| Sets the operating protocol:

Proprietary if n=0

MODBUS-RTU if n=1
Default
: MODBUS-RTU (n=1)
RP & n| Reads the operating protocol set in the instrument.
SM &| Activates the MODBUS-RTU protocol immediately.
CMAn &| Sets the instrument address for the MODBUS-RTU pro-
tocol to n.
The address should range within 1 and 247.
Default : 1
RMA & n| Reads the instrument address for the MODBUS-RTU pro-
tocol.