Sensors WSTP11A User Guide

Industrial Unibody Temperature Transmitter, High Accuracy, Stainless Steel Probe, Water-Proof & Dust-Proof, RS485 Bus


  • Digital output, via RS485 (standard Modbus-RTU protocol)
  • Wide range input voltage, non-linear correction, high accuracy
  • Small size, light weight, easy installation
  • Lightning-proof,cut-off frequency interference design, strong anti-interference capability
  • Reverse proof, over voltage protection, and current limited protection
  • Measurement accuracy up to 0.5% FS


  • Measured Medium:Liquid, gas
  • Accuracy: 0.5%FS
  • Full weight: 180g
  • Stability: ±0.1% FS/year
  • Measurement range: -50~100℃
  • Protection rating: IP65
  • Power supply: 12~36V DC
  • Ambient temperature: -40~85℃
  • Output signal: RS485 (standard Modbus-RTU protocol)
  • Ambient humidity:0%~95% RH(non-condensing, non-frosting)
  • Material:
    • Probe: 304 stainless steel (contacted)
    • Intermediate junction: 304 stainless steel (contacted)
    • Shell: 304 stainless steel
    • Hirschmann connector: ABS engineering plastics


Hesman interface

Communication Protocol

Modbus protocol is a universal language used in industrial electronic controllers. Modbus supports communication to and from multiple devices connected to the same cable or Ethernet network, it has become a standard communication protocol. With the Modbus, control equipment produced by different manufactures can be connected to the sam industrial network for centralized monitoring. The protocol defines a message structure, which can be recognized and used by the controller through any network. It describes the process of a controller requesting access to other devices, how to respond to requests from other devices, and how to detect and record errors. It has formulated a common format for the structure and content of the message domain.
Advantage of Modbus: (1)It is a standard protocol, open-sources, and free to use. (2)Modbus protocol support RS-232, RS-485 bus, and so on. (3)The format of Modbus is simple and easy to use.

Modbus parameters of WSSP08A (the device address is default 01)

This sensor is compatible with Modbus RTU. The RS485 port is half-duplex.
a) Output signal: RS485 (Communication distance is up to 1000m. Support multi-connect 32 devices)
b) Standard Modbus-RTU protocol (03: Read data; 06: Write setting data)<br /? c) Data format: 9600, N, 8, 1
d) Measure range: 0-X(MPa, kPa...)
e) Accuracy: 0.05%
f) Output data: 0...2000(range is customizable)
g) Response frequency: ≤5Hz
h) Response speed: ≥10ms

0x03: Read data (HEX)

WSSP08A format-1.png

Examples 1
Read sensor

The device address of 0-1.6Mpa sensor is 0x01, that is [Address]=01 (The Address range 01-254)
CRC0=84 and CRC1=0a, then the commands will be:
Command: 01 03 00 00 00 01 84 0A
Response: 01 03 02 02 AC B9 59
Convert 02AC to DEC, you will get the data 684;
Because the data range is 0-2000, related to the pressure range 0-1.6Mpa, the pressure read is P = 1.6*684/2000=0.5472MPa
The formula: (The maximum range - the minimum range) /2000 * Current data + minumin ranage = current pressure.

Examples 2
Read device address (This command only work for a single sensor)

Command: FF 03 00 0F 00 01 A1 D7
Response: FF 03 02 00 01 50 50
That is: The device address is 01

0x06: Write data (HEX)

WSSP08A format-2.png

Modify the device address from 01 to 09

Command: 01 06 00 0F 00 09 79 CF
Response: 01 06 00 0F 00 09 79 CD
The modification will be valid without a restart.


Pull out the terminal block which is inside the casing of the plug to connect the wire, wiring steps areas shown in the following figure.

Wiring diagram

Price: $39.89
Part Number: WSTP11A
Brand: Spotpear
SKU: 0205022