Call Service

R2026b

Call service in ROS network

• 

Call Service ROS 1 block

To add a block to a model, double-click the canvas and start typing the block name. Then, select the block from the list.

Libraries:
ROS Toolbox / ROS

Description

The Call Service block takes a ROS service request message, sends it to the ROS service server, and waits for a response. Connect to a ROS network using rosinit. A ROS server should be set up somewhere on the network before using this block. Check the available services on a ROS network using rosservice. Use rossvcserver to set up a service server in MATLAB^®.

Specify the name for your ROS service and the service type in the block mask. If connected to a ROS network, you can select from a list of available services. You can create a blank service request or response message to populate with data using the Blank Message block.

Examples

Call ROS Service in Simulink

Use the Call Service block to call a service on the ROS service server.

• Open Live Script

Ports

Input

Req — Request message

nonvirtual bus

Request message, specified as a nonvirtual bus. The request message type corresponds to your service type. To generate an empty request message bus to populate with data, use the Blank Message block.

Data Types: bus

Output

Resp — Response message

nonvirtual bus

Response message, returned as a nonvirtual bus. The response is based on the input Req message. The response message type corresponds to your service type. To generate an empty response message bus to populate with data, use the Blank Message block.

Data Types: bus

ErrorCode — Error conditions for service call

integer

Error conditions for service call, specified as an integer. Each integer corresponds to a different error condition for the service connection or the status of the service call. If an error condition occurs, Resp outputs the last response message or a blank message if a response was not previously received.

Error Code	Condition
0	The service response was successfully retrieved and is available in the Resp output.
1	The connection was not established within the specified Connection timeout.
2	The response from the server was not received.
3	The service call failed for unknown reasons.

Dependencies

This output is enabled when the Show ErrorCode output port check box is on.

Data Types: uint8

Parameters

Source — Source for specifying service name

Select from ROS network | Specify your own

Source for specifying the service name:

• Select from ROS network — Use Select to select a service name. The Name and Type parameters are set automatically. You must be connected to a ROS network.

• Specify your own — Enter a service name in Name and specify its service type in Type. You must match a service name exactly.

Name — Service name

character vector

Service name, specified as a character vector. The service name must match a service name available on the ROS service server. To see a list of valid services in a ROS network, see rosservice.

Type — Service type

character vector

Service type, specified as a character vector. Each service name has a corresponding type.

Connection timeout — Timeout for service server connection

5 (default) | positive numeric scalar

Timeout for service server connection, specified as a positive numeric scalar in seconds. If a connection cannot be established with the ROS service server in this time, then ErrorCode outputs 1.

Keep persistent connection — Keep connection to service server

off (default) | on

Check this box to maintain a persistent connection with the ROS service server. When off, the block creates a service client every time a request message is input into Req.

Show ErrorCode output port — Enable error code output port

on (default) | off

Check this box to output the ErrorCode output. If an error condition occurs, Resp outputs the last response message or a blank message if response was not previously received.

Programmatic Use: Add Block

To add the block programmatically, use the add_block function with one of these library block paths as the source.

"robotlib/Call Service"

Example: add_block("robotlib/Call Service","myModel/myBlock",MakeNameUnique="on")

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2019b