Step 1: Create a connection for Zoho FSM in Zoho Books  

1. Log in to Zoho Books.
   
2. Navigate to Settings > Developer Space > Connections and click New Connection.
   
   
   
   
3. In the Create Connection page, select the Custom Services tab and click Create New Service.
   
   
   
   
4. In the Create Service page, enter the following details and click Create Service.
   
1. Service Name: Zoho FSM
   The Service Link Name will be automatically populated.
2. Authentication Type: OAuth2
   
3. Parameter Type: Header
   
4. Generated Client ID, Client Secret
   
5. Authorize URL: https://accounts.zoho.com/oauth/v2/auth?access_type=offline&prompt=consent
   
6. Access Token URL: https://accounts.zoho.com/oauth/v2/token
   
7. Refresh Token URL: https://accounts.zoho.com/oauth/v2/token
   
8. Scope: ZohoFSM.modules.all
   Provide a Scope Display Name.
   
   
   
   
5. Click Create Connection.
   
6. Do the following and click Create And Connect:
   Connection Name: Zoho FSM
   Select the Scope ZohoFSM.modules.all.
   
   

Additionally ensure that the status of the internal connection for Zoho Books Integration tasks is Connected. The green dot [] indicates that the connection is Connected.

Step 2: Create a custom function in Zoho Books  

1. Navigate to Settings > Automation > Custom Functions and click New Custom Function.
   
   
   
   
2. Enter the following details and click Save:
   
1. Function Name: createwofrombooks
   
2. Module: Invoice
   
3. In the Deluge Script Editor, enter this script.
   

Step 3: Create a workflow rule in Zoho Books   

1. Navigate to Settings > Automation > Workflow Rules and click New Workflow Rule.
   
   
   
   
2. In the New Workflow Rule screen, enter the following details and click Next:
   
1. Workflow Rule Name: CreateWOInZFSM
   
2. Module: Invoice
   
   
   
   
3. For Choose when to Trigger, enter the following details and click Next.
   
1. Workflow type: Event Based
   
2. When an Estimate is: Created
   
   
   
   
4. Click Next for Filter the triggers.
5. In the Actions section, do the following:
   
1. Type: Custom Functions
   
2. Name: The function created in the previous step.
   
   
   
   
6. Click Save.
   

Testing the use case  

1. Navigate to Sales > Invoices and click New.
   
   
   
   
2. Enter the necessary details and save (Save as Draft, Save and Send, etc.) the invoice.
   Ensure that the contact you choose is present in Zoho FSM. A Service Address, Billing Address, and Email should be present for the contact. Since a work order in Zoho FSM should have atleast one service, ensure that you add to the invoice a service that is present in Zoho FSM. If there are no services in your invoice, in Zoho FSM create a dummy service with Unit Price zero, and add it to the invoice.