-32-
Drawing No. LP0932
Released 2018-01-12
SERIAL COMMUNICATIONS
When using a PXU with RS485 communications option, the PXU will support Modbus communications. Unit
configuration, as well as data interrogation, can be accomplished through Modbus communications. The PXU
allows for 32 Read / Write registers. A complete list of Modbus registers is available at the end of this document.
CRIMSON SOFTWARE
Crimson is a Windows
®
based program that allows configuration of
the PXU controller from a PC. Crimson offers standard drop-down menu
commands to make it easy to program the PXU controller, the PXU
database can then be saved in a PC file for future use. The Crimson 2.1
software is available at www.redlion.net. An RS-485 PC card or USB to
RS485 converter and cabling is required. Prior to downloading or
extracting the database, the PXU must be set to Modbus RTU
communications type. The proper communications port, baud rate, and
unit address must be configured in the Link, Options dialog and must
match the baud rate and unit address configured in the PXU serial
communications module (
-C
).
PXU CONFIGURATION USING CRIMSON
1. Install Crimson software, available for download at www.redlion.net.
2. Connect communications cable from PXU to PC.
3. Supply power to PXU.
4. Configure serial parameters as Modbus RTU (
rtu
), 38,400 baud,
address 247.
5. Create a new file (File, New) or open an existing PXU database within
Crimson.
6. Configure Crimson 2 Link options (Link, Options) to the serial port
which the communication cable is attached (in step 2).
7. Select Update (Link, Update).
PXU FREQUENTLY USED MODBUS REGISTERS
Only frequently used registers are shown below. The entire Modbus Register Table can be found at the end of this document.
The following is an example of the necessary query and corresponding response for holding register 2. In this example register 2 is the decimal value
123.
Query: 01 03 00 01 00 01 D5 CA
Response: 01 03 02 00 7B F8 67
Notes:
1. The PXU registers can be read as holding (4x) or input (3x) registers.
2. The PXU should not be powered down while parameters are being changed. Doing so may result in an incomplete write to the non-volatile memory
and produce checksum errors.
REGISTER (4x)
REGISTER NAME
LOW LIMIT
HIGH LIMIT
FACTORY
SETTING
ACCESS
COMMENTS
1
Process Value (PV)
N/A
N/A
N/A
Read
1 = 1 Display unit
2
Active Setpoint (SP)
-999
9999
0
Read/Write 1 = 1 Display unit
3
Setpoint 1 (SP1)
-999
9999
0
Read/Write 1 = 1 Display unit
4
Setpoint 2 (SP2)
-999
9999
0
Read/Write 1 = 1 Display unit
5
Setpoint Deviation
N/A
N/A
N/A
Read Only 1 = 1 Display unit
6
Alarm 1 Value
-999
9999
100
Read/Write 1 = 1 Display unit
7
Alarm 2 Value
-999
9999
200
Read/Write 1 = 1 Display unit
8
Alarm 3 Value
-999
9999
300
Read/Write 1 = 1 Display unit
9
Output Power 1
0
1000
0
Read/Write 1 = 0.1%; writable when in manual mode only.
10
Output Power 2
0
1000
0
Read/Write 1 = 0.1%; writable when in manual mode only.
11
PB Proportional band (Active)
1
999(.9)° or
9999 (process)
70
Read/Write 1 = 1 Display unit
12
Integral time (Active)
0
9999
120
Read/Write 1 = 1 second
13
Derivative time (Active)
0
9999
30
Read/Write 1 = 1 second
14
Integration default (Active)
0
1000
0
Read/Write 1 = 0.1 % output power
15
PID parameter set selection
0
1
0
Read/Write 0 = PID Set 1, 1 = PID Set 2
16
Auto-Tune Start
0
1
0
Read/Write 0 = No; 1 = Yes
17
Control Mode Transfer (Auto/Manual)
0
1
0
Read/Write 0 = Automatic (PID), 1 = User (Manual Mode)
18
Controller Status
0
1
1
Read/Write 0: Stop, 1: Run
19
Setpoint Select
0
1
0
Read/Write 0=SP1, 1=SP2
20
SP Ramp Rate
0
9999
0
Read/Write 1 = 1 Display unit/minute
21
LED Status
N/A
N/A
N/A
Read Only b0: ALM3, b1: ALM2, b2: F, b3: C, b4: ALM1,
b5: OUT2, b6:OUT1, b7: AT
22
Pushbutton Status
N/A
N/A
N/A
Read Only b1: F2, b2: Down, b3: P, b5: F1, b6: Up, b7: D;
0 = Key pressed, 1 = Key not pressed
23
Alarm Reset
0
7
0
Write
b0: Reset Alm1, b1: Reset Alm2, b3: Reset Alm3
24
Setpoint Ramping Disable
0
1
0
Read/Write 0 = Enabled, 1 = Disabled
