Take the USDT contract on Shasta test net as an example，Use Tronweb and wallet-cli to call the TRC-20 interface of the contract, respectively.

Some related links:
Find the USDT on Tronscan
Code conversion tool

We can use the triggersmartcontract function to call constant functions in the contract to get the result directly without broadcasting.
Please set supportConstant = true in your node config.

name

Call the name function to get the name of the token.

HTTP API :

/wallet/triggerconstantcontract
Description: Trigger the constant of the smart contract, the transaction is off the blockchain
demo: curl -X POST  https://127.0.0.1:8090/wallet/triggerconstantcontract -d '{
"contract_address":"419E62BE7F4F103C36507CB2A753418791B1CDC182",
"function_selector":"name()",
"owner_address":"41977C20977F412C2A1AA4EF3D49FEE5EC4C31CDFB"
}'

Tronweb Example:

const TronWeb = require('tronweb')

const HttpProvider = TronWeb.providers.HttpProvider;
const fullNode = new HttpProvider("https://127.0.0.1:8090");
const solidityNode = new HttpProvider("https://127.0.0.1:8090");
const eventServer = new HttpProvider("https://127.0.0.1:8090");
const privateKey = "your private key";
const tronWeb = new TronWeb(fullNode,solidityNode,eventServer,privateKey);

async function triggerSmartContract() {
    const trc20ContractAddress = "TQQg4EL8o1BSeKJY4MJ8TB8XK7xufxFBvK";//contract address

    try {
        let contract = await tronWeb.contract().at(trc20ContractAddress);
        //Use call to execute a pure or view smart contract method.
        // These methods do not modify the blockchain, do not cost anything to execute and are also not broadcasted to the network.
        let result = await contract.name().call();
        console.log('result: ', result);
    } catch(error) {
        console.error("trigger smart contract error",error)
    }
}

Wallet-cli Example:

TriggerConstantContract TQQg4EL8o1BSeKJY4MJ8TB8XK7xufxFBvK name() # false

Usage : TriggerConstantContract [ownerAddress] [contractAddress] [method] [args] [isHex]
Parameter Description：
ownerAddress: calller address
contractAdress：TRC20 contract address
method： contract function
args：function parameters，If there is no parameter,use # placeholder
isHex： whether the address of the command parameter is in hex format

symbol

Call the symbol function to get the symbol of the token.

HTTP API :

/wallet/triggerconstantcontract
Description: Trigger the constant of the smart contract, the transaction is off the blockchain
demo: curl -X POST  https://127.0.0.1:8090/wallet/triggerconstantcontract -d '{
"contract_address":"419E62BE7F4F103C36507CB2A753418791B1CDC182",
"function_selector":"symbol()",
"owner_address":"41977C20977F412C2A1AA4EF3D49FEE5EC4C31CDFB"
}'

Tronweb Example:

const TronWeb = require('tronweb')

const HttpProvider = TronWeb.providers.HttpProvider;
const fullNode = new HttpProvider("https://127.0.0.1:8090");
const solidityNode = new HttpProvider("https://127.0.0.1:8090");
const eventServer = new HttpProvider("https://127.0.0.1:8090");
const privateKey = "your private key";
const tronWeb = new TronWeb(fullNode,solidityNode,eventServer,privateKey);

async function triggerSmartContract() {
    const trc20ContractAddress = "TQQg4EL8o1BSeKJY4MJ8TB8XK7xufxFBvK";//contract address

    try {
        let contract = await tronWeb.contract().at(trc20ContractAddress);
        //Use call to execute a pure or view smart contract method.
        // These methods do not modify the blockchain, do not cost anything to execute and are also not broadcasted to the network.
        let result = await contract.symbol().call();
        console.log('result: ', result);
    } catch(error) {
        console.error("trigger smart contract error",error)
    }
}

Wallet-cli Example:

TriggerConstantContract TQQg4EL8o1BSeKJY4MJ8TB8XK7xufxFBvK symbol() # false

decimals

Call the decimals function to get the precision of the token.

HTTP API :

/wallet/triggerconstantcontract
Description: Trigger the constant of the smart contract, the transaction is off the blockchain
demo: curl -X POST  https://127.0.0.1:8090/wallet/triggerconstantcontract -d '{
"contract_address":"419E62BE7F4F103C36507CB2A753418791B1CDC182",
"function_selector":"decimals()",
"owner_address":"41977C20977F412C2A1AA4EF3D49FEE5EC4C31CDFB"
}'

Tronweb Example:

const TronWeb = require('tronweb')

const HttpProvider = TronWeb.providers.HttpProvider;
const fullNode = new HttpProvider("https://127.0.0.1:8090");
const solidityNode = new HttpProvider("https://127.0.0.1:8090");
const eventServer = new HttpProvider("https://127.0.0.1:8090");
const privateKey = "your private key";
const tronWeb = new TronWeb(fullNode,solidityNode,eventServer,privateKey);

async function triggerSmartContract() {
    const trc20ContractAddress = "TQQg4EL8o1BSeKJY4MJ8TB8XK7xufxFBvK";//contract address

    try {
        let contract = await tronWeb.contract().at(trc20ContractAddress);
        //Use call to execute a pure or view smart contract method.
        // These methods do not modify the blockchain, do not cost anything to execute and are also not broadcasted to the network.
        let result = await contract.decimals().call();
        console.log('result: ', result);
    } catch(error) {
        console.error("trigger smart contract error",error)
    }
}

Wallet-cli Example:

TriggerConstantContract TQQg4EL8o1BSeKJY4MJ8TB8XK7xufxFBvK decimals() # false

totalSupply

Call the totalSupply function to get the total supply of the token.

HTTP API :

/wallet/triggerconstantcontract
Description: Trigger the constant of the smart contract, the transaction is off the blockchain
demo: curl -X POST  https://127.0.0.1:8090/wallet/triggerconstantcontract -d '{
"contract_address":"419E62BE7F4F103C36507CB2A753418791B1CDC182",
"function_selector":"totalSupply()",
"owner_address":"41977C20977F412C2A1AA4EF3D49FEE5EC4C31CDFB"
}'

Tronweb Example:

const TronWeb = require('tronweb')

const HttpProvider = TronWeb.providers.HttpProvider;
const fullNode = new HttpProvider("https://127.0.0.1:8090");
const solidityNode = new HttpProvider("https://127.0.0.1:8090");
const eventServer = new HttpProvider("https://127.0.0.1:8090");
const privateKey = "your private key";
const tronWeb = new TronWeb(fullNode,solidityNode,eventServer,privateKey);

async function triggerSmartContract() {
    const trc20ContractAddress = "TQQg4EL8o1BSeKJY4MJ8TB8XK7xufxFBvK";//contract address

    try {
        let contract = await tronWeb.contract().at(trc20ContractAddress);
        //Use call to execute a pure or view smart contract method.
        // These methods do not modify the blockchain, do not cost anything to execute and are also not broadcasted to the network.
        let result = await contract.totalSupply().call();
        console.log('result: ', result);
    } catch(error) {
        console.error("trigger smart contract error",error)
    }
}

Wallet-cli:

TriggerConstantContract TQQg4EL8o1BSeKJY4MJ8TB8XK7xufxFBvK totalSupply() # false

balanceOf

Call the balanceOf function to get the token balance of the specified account.

HTTP API :

/wallet/triggerconstantcontract
Description: Trigger the constant of the smart contract, the transaction is off the blockchain
demo: curl -X POST https://127.0.0.1:8090/wallet/triggerconstantcontract -d '{
"contract_address":"419E62BE7F4F103C36507CB2A753418791B1CDC182",
"function_selector":"balanceOf(address)",
"parameter":"000000000000000000000041977C20977F412C2A1AA4EF3D49FEE5EC4C31CDFB",
"owner_address":"41977C20977F412C2A1AA4EF3D49FEE5EC4C31CDFB"
}'

Tronweb Example:

const TronWeb = require('tronweb')

const HttpProvider = TronWeb.providers.HttpProvider;
const fullNode = new HttpProvider("https://127.0.0.1:8090");
const solidityNode = new HttpProvider("https://127.0.0.1:8090");
const eventServer = new HttpProvider("https://127.0.0.1:8090");
const privateKey = "your private key";
const tronWeb = new TronWeb(fullNode,solidityNode,eventServer,privateKey);

async function triggerSmartContract() {
    const trc20ContractAddress = "TQQg4EL8o1BSeKJY4MJ8TB8XK7xufxFBvK";//contract address
    var address = "TM2TmqauSEiRf16CyFgzHV2BVxBe...";

    try {
        let contract = await tronWeb.contract().at(trc20ContractAddress);
        //Use call to execute a pure or view smart contract method.
        // These methods do not modify the blockchain, do not cost anything to execute and are also not broadcasted to the network.
        let result = await contract.balanceOf(address).call();
        console.log('result: ', result);
    } catch(error) {
        console.error("trigger smart contract error",error)
    }
}

Wallet-cli Example:

TriggerConstantContract TQQg4EL8o1BSeKJY4MJ8TB8XK7xufxFBvK balanceOf(address) "TM2TmqauSEiRf16CyFgzHV2BVxBejY9iyR" false

transfer

Call transfer function for token transfer

HTTP API :

wallet/triggersmartcontract
Description: Trigger smart contract
demo: curl -X POST https://127.0.0.1:8090/wallet/triggersmartcontract -d '{
"contract_address":"419E62BE7F4F103C36507CB2A753418791B1CDC182",
"function_selector":"transfer(address,uint256)",
"parameter":"00000000000000000000004115208EF33A926919ED270E2FA61367B2DA3753DA0000000000000000000000000000000000000000000000000000000000000032",
"fee_limit":100000000,
"call_value":0,
"owner_address":"41977C20977F412C2A1AA4EF3D49FEE5EC4C31CDFB"
}'

The parameter is to encode address and uint256 in transfer (address,uint256), please refer to the parameter encoding and decoding document
Note: After calling this HTTP API, you also need to call the signature and broadcast APIs.

Tronweb Example:

const TronWeb = require('tronweb')

const HttpProvider = TronWeb.providers.HttpProvider;
const fullNode = new HttpProvider("https://127.0.0.1:8090");
const solidityNode = new HttpProvider("https://127.0.0.1:8090");
const eventServer = new HttpProvider("https://127.0.0.1:8090");
const privateKey = "your private key";
const tronWeb = new TronWeb(fullNode,solidityNode,eventServer,privateKey);

async function triggerSmartContract() {
    const trc20ContractAddress = "TQQg4EL8o1BSeKJY4MJ8TB8XK7xufxFBvK";//contract address
    var address = "TM2TmqauSEiRf16CyFgzHV2BVxBe...";

    try {
        let contract = await tronWeb.contract().at(trc20ContractAddress);
        //Use send to execute a non-pure or modify smart contract method on a given smart contract that modify or change values on the blockchain.
        // These methods consume resources(bandwidth and energy) to perform as the changes need to be broadcasted out to the network.
        let result await contract.transfer(
            "TVDGp...", //address _to
            1000000   //amount
        ).send({
            feeLimit: 1000000
        }).then(output => {console.log('- Output:', output, '\n');});
        console.log('result: ', result);
    } catch(error) {
        console.error("trigger smart contract error",error)
    }
}

Wallet-cli Example:

TriggerContract TQQg4EL8o1BSeKJY4MJ8TB8XK7xufxFBvK  transfer(address,uint256) "TBQDyqoJ2ZJHTRDsrGQasyqBm4nUVLbWee",100 false 100000000 0 0 #

Usage ：
TriggerContract [ownerAddress] [contractAddress] [method] [args] [isHex] [fee_limit] [value] [token_value] [token_id]
Parameter Description：
ownerAddress: calller address
contractAdress：TRC20 contract address
method： contract function
args：function parameters，If there is no parameter,use # placeholder
isHex： whether the address of the command parameter is in hex format
fee_limit: the maximum trx consumption of this calling, the unit is sun
value: the amount of TRX that transfered to the contract while calling the contract, the unit is sun
token_value: the amount of TRC10 asset that transfered to the contract while calling the contract
token_id:the TRC10 asset ID that transfered to the contract while calling the contract

Transaction confirmation：
Check whether the transfer of TRC20 was successful according to result of getTransactionInfoById.

approve

Call the approve function to authorize a certain amount of token use rights to other addresses.

HTTP API :

wallet/triggersmartcontract
Description: Trigger smart contract
demo: curl -X POST https://127.0.0.1:8090/wallet/triggersmartcontract -d '{
"contract_address":"419E62BE7F4F103C36507CB2A753418791B1CDC182",
"function_selector":"approve(address,uint256)",
"parameter":"0000000000000000000000410FB357921DFB0E32CBC9D1B30F09AAD13017F2CD0000000000000000000000000000000000000000000000000000000000000064",
"fee_limit":100000000,
"call_value":0,
"owner_address":"41977C20977F412C2A1AA4EF3D49FEE5EC4C31CDFB"
}'

Note: After calling this HTTP API, you also need to call the signature and broadcast APIs.

Tronweb Example:

const TronWeb = require('tronweb')

const HttpProvider = TronWeb.providers.HttpProvider;
const fullNode = new HttpProvider("https://127.0.0.1:8090");
const solidityNode = new HttpProvider("https://127.0.0.1:8090");
const eventServer = new HttpProvider("https://127.0.0.1:8090");
const privateKey = "your private key";
const tronWeb = new TronWeb(fullNode,solidityNode,eventServer,privateKey);

async function triggerSmartContract() {
    //User A allows user B to use 10USDT of A: A calls approve (B,10)
    const trc20ContractAddress = "TQQg4EL8o1BSeKJY4MJ8TB8XK7xufxFBvK";//contract address

    try {
        let contract = await tronWeb.contract().at(trc20ContractAddress);
        //Use send to execute a non-pure or modify smart contract method on a given smart contract that modify or change values on the blockchain.
        // These methods consume resources(bandwidth and energy) to perform as the changes need to be broadcasted out to the network.
        await contract.approve(
            "TA1g2WQiXbU...", //address _spender
            10000000 //amount
        ).send({
            feeLimit: 100000000
        }).then(output => {console.log('- Output:', output, '\n');});
    } catch(error) {
        console.error("trigger smart contract error",error)
    }
}

Wallet-cli Example:

TriggerContract TQQg4EL8o1BSeKJY4MJ8TB8XK7xufxFBvK  approve(address,uint256) "TBQDyqoJ2ZJHTRDsrGQasyqBm4nUVLbWee",100 false 100000000 0 0 #

Transaction confirmation：
Check whether the transfer of TRC20 was successful according to result of getTransactionInfoById.

transferFrom

Authorized addresses calling the transferFrom function to transfer tokens from autherizer's account.

HTTP API :

wallet/triggersmartcontract
Description: Trigger smart contract
demo: curl -X POST https://127.0.0.1:8090/wallet/triggersmartcontract -d '{
"contract_address":"419E62BE7F4F103C36507CB2A753418791B1CDC182",
"function_selector":"transferFrom(address,address,uint256)",
"parameter":"00000000000000000000004109669733965A37BA3582E70CCC5302F8D254675D0000000000000000000000410FB357921DFB0E32CBC9D1B30F09AAD13017F2CD0000000000000000000000000000000000000000000000000000000000000032",
"fee_limit":100000000,
"call_value":0,
"owner_address":"41977C20977F412C2A1AA4EF3D49FEE5EC4C31CDFB"
}'

Note: After calling this HTTP API, you also need to call the signature and broadcast APIs.

Tronweb Example:

const TronWeb = require('tronweb')

const HttpProvider = TronWeb.providers.HttpProvider;
const fullNode = new HttpProvider("https://127.0.0.1:8090");
const solidityNode = new HttpProvider("https://127.0.0.1:8090");
const eventServer = new HttpProvider("https://127.0.0.1:8090");
const privateKey = "your private key";
const tronWeb = new TronWeb(fullNode,solidityNode,eventServer,privateKey);

async function triggerSmartContract() {
    // Address B transfers 10 USDT from address A to C: B calls transferFrom (A, C, 10)
    const trc20ContractAddress = "TQQg4EL8o1BSeKJY4MJ8TB8XK7xufxFBvK";//contract address

    try {
        let contract = await tronWeb.contract().at(trc20ContractAddress);
        //Use send to execute a non-pure or modify smart contract method on a given smart contract that modify or change values on the blockchain.
        // These methods consume resources(bandwidth and energy) to perform as the changes need to be broadcasted out to the network.
        await contract.transferFrom(
            "TM2TmqauSEiRf16CyFgzHV2BVxBej...", //address _from
            "TVDGpn4hCSzJ5nkHPLetk8KQBtwaT...", //address _to
            100000 //amount
        ).send({
            feeLimit: 10000000
        }).then(output => {console.log('- Output:', output, '\n');});
    } catch(error) {
        console.error("trigger smart contract error",error)
    }
}

Wallet-cli Example:

TriggerContract TQQg4EL8o1BSeKJY4MJ8TB8XK7xufxFBvK  transferFrom(address,address,uint256) "TApuyuazZnGgxvbNbaGcrUijEFn1oidsAH","TBQDyqoJ2ZJHTRDsrGQasyqBm4nUVLbWee",50 false 100000000 0 0 #

Transaction confirmation：
Check whether the transfer of TRC20 was successful according to result of getTransactionInfoById.

allowance

Authorized addresses call the allowance function to query the balance of authroized amount.

HTTP API :

/wallet/triggerconstantcontract
Description: Trigger the constant of the smart contract, the transaction is off the blockchain
demo: curl -X POST https://127.0.0.1:8090/wallet/triggersmartcontract -d '{
"contract_address":"419E62BE7F4F103C36507CB2A753418791B1CDC182",
"function_selector":"allowance(address,address)",
"parameter":"00000000000000000000004109669733965A37BA3582E70CCC5302F8D254675D000000000000000000000041A245B99ECB47B18C6A90ED1D51100C5A9F0641A7",
"owner_address":"41977C20977F412C2A1AA4EF3D49FEE5EC4C31CDFB"
}'

Tronweb Example:

const TronWeb = require('tronweb')

const HttpProvider = TronWeb.providers.HttpProvider;
const fullNode = new HttpProvider("https://127.0.0.1:8090");
const solidityNode = new HttpProvider("https://127.0.0.1:8090");
const eventServer = new HttpProvider("https://127.0.0.1:8090");
const privateKey = "your private key";
const tronWeb = new TronWeb(fullNode,solidityNode,eventServer,privateKey);

async function triggerSmartContract() {
    //Query the USDT balance that Account A can use for Account B: Account B calls allowance (A, B)
    const trc20ContractAddress = "TQQg4EL8o1BSeKJY4MJ8TB8XK7xufxFBvK";//contract address

    try {
        let contract = await tronWeb.contract().at(trc20ContractAddress);
        //Use send to execute a non-pure or modify smart contract method on a given smart contract that modify or change values on the blockchain.
        // These methods consume resources(bandwidth and energy) to perform as the changes need to be broadcasted out to the network.
        const value = await contract.allowance(
            "TM2TmqauSEiRf16CyFgzHV2BVxBejY9...", //address _owner
            "TA1g2WQiXbU5GnYBTJ5Cp22dvSjT3ug..." //address _spender
        ).call();
        console.log('- Output:', value, '\n');
    } catch(error) {
        console.error("trigger smart contract error",error)
    }
}

Wallet-cli Example:

TriggerConstantContract TQQg4EL8o1BSeKJY4MJ8TB8XK7xufxFBvK allowance(address,address) "TApuyuazZnGgxvbNbaGcrUijEFn1oidsAH","TQmDzierQxEFJm1dT5YXnTXqVAfdN9HtXj" false