Call Service

Call service in ROS network

  • Library:
  • 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.

Ports

Input

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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

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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

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 CodeCondition
0The service response was successfully retrieved and is available in the Resp output.
1The connection was not established within the specified Connection timeout.
2The response from the server was not received within the specified Call timeout
3The 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

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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.

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.

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

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.

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.

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.

Introduced in R2019b