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samples: modbus: add user function code example

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Demonstrate user function codes with a simple example with a user defined
fc that maps to a function that just increments a counter every time it's
read.

Signed-off-by: Henrik Lindblom <henrik.lindblom@vaisala.com>
This commit is contained in:
Henrik Lindblom 2023-03-05 09:48:48 +02:00 committed by Carles Cufí
parent 01757cfd32
commit 1f65c9be87
1 changed files with 45 additions and 1 deletions
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46
samples/subsys/modbus/tcp_server/src/main.c
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@ -26,6 +26,43 @@ static const struct gpio_dt_spec led_dev[] = {
GPIO_DT_SPEC_GET(DT_ALIAS(led2), gpios),
};
static int custom_read_count;
static bool custom_handler(const int iface,
const struct modbus_adu *rx_adu,
struct modbus_adu *tx_adu,
uint8_t *const excep_code,
void *const user_data)
{
const uint8_t request_len = 2;
const uint8_t response_len = 6;
int *read_counter = (int *)user_data;
uint8_t subfunc;
uint8_t data_len;
LOG_INF("Custom Modbus handler called");
if (rx_adu->length != request_len) {
LOG_WRN("Custom request length doesn't match");
*excep_code = MODBUS_EXC_ILLEGAL_DATA_VAL;
return true;
}
subfunc = rx_adu->data[0];
data_len = rx_adu->data[1];
LOG_INF("Custom function called with subfunc=%u, data_len=%u", subfunc, data_len);
(*read_counter)++;
sys_put_be16(0x5555, tx_adu->data);
sys_put_be16(0xAAAA, &tx_adu->data[2]);
sys_put_be16(*read_counter, &tx_adu->data[4]);
tx_adu->length = response_len;
return true;
}
MODBUS_CUSTOM_FC_DEFINE(custom, custom_handler, 101, &custom_read_count);
static int init_leds(void)
{
int err;
@ -155,6 +192,7 @@ const static struct modbus_iface_param server_param = {
static int init_modbus_server(void)
{
char iface_name[] = "RAW_0";
int err;
server_iface = modbus_iface_get_by_name(iface_name);
@ -164,7 +202,13 @@ static int init_modbus_server(void)
return -ENODEV;
}
return modbus_init_server(server_iface, server_param);
err = modbus_init_server(server_iface, server_param);
if (err < 0) {
return err;
}
return modbus_register_user_fc(server_iface, &modbus_cfg_custom);
}
static int modbus_tcp_reply(int client, struct modbus_adu *adu)