Support for Device Identification

example/example.c

@@ -116,6 +116,10 @@ void modbusGet(void) {
 				modbusExchangeRegisters(holdingRegisters,0,4);
 			}
 			break;
+			case fcEncapsulatedInterfaceTransport:
+			{
+				modbusHandleDeviceId();
+			}
 
 			default: {
 				modbusSendException(ecIllegalFunction);

yaMBSiavr.c

@@ -426,3 +426,31 @@ uint8_t modbusExchangeBits(volatile uint8_t *ptrToInArray, uint16_t startAddress
 		return 0;
 	}
 }
+
+uint8_t modbusCopyMeiObj(volatile unsigned char* buff, uint8_t obj_id, const __flash char* obj_str, uint8_t obj_len)
+{
+    obj_len--; // modbus ignores the null-termination
+    *buff++ = obj_id;
+    *buff++ = obj_len;
+    for(uint8_t i = 0; i < obj_len; i++)
+    {
+        *buff++ = *obj_str++;
+    }
+    return obj_len + 2;
+}
+
+void modbusHandleDeviceId()
+{
+    rxbuffer[4] = 0x01; // conformity level
+    rxbuffer[5] = 0x00; // more follows: no
+    rxbuffer[6] = 0x00; // next object id: none
+    rxbuffer[7] = 0x03; // number of objects
+
+    uint8_t offset = 8;
+
+    offset += modbusCopyMeiObj(&rxbuffer[offset], 0, modbus_dev_vendor, sizeof(modbus_dev_vendor));
+    offset += modbusCopyMeiObj(&rxbuffer[offset], 1, modbus_dev_product, sizeof(modbus_dev_product));
+    offset += modbusCopyMeiObj(&rxbuffer[offset], 2, modbus_dev_version, sizeof(modbus_dev_version));
+
+    modbusSendMessage(offset - 1);
+}

yaMBSiavr.h

@@ -38,6 +38,7 @@ THE POSSIBILITY OF SUCH DAMAGE.
 
 ************************************************************************/
 #include <avr/io.h>
+#include <avr/pgmspace.h>
 /** 
  *  @code #include <yaMBSIavr.h> @endcode
  * 
@@ -55,6 +56,10 @@ THE POSSIBILITY OF SUCH DAMAGE.
 #define BAUD 38400L
 #endif
 
+#define MODBUS_DEV_VENDOR "Your Company"
+#define MODBUS_DEV_PRODUCT "Your Device Name"
+#define MODBUS_DEV_VERSION "V0.1beta"
+
 /*
 * Definitions for transceiver enable pin.
 */
@@ -256,6 +261,7 @@ THE POSSIBILITY OF SUCH DAMAGE.
 #define fcForceMultipleCoils 15 //write multiple bits
 #define fcPresetMultipleRegisters 16 //write multiple analog output registers (2 Bytes each)
 #define fcReportSlaveID 17 //read device description, run status and other device specific information
+#define fcEncapsulatedInterfaceTransport 43 //device identification
 
 /**
  * @brief    Modbus Exception Codes
@@ -381,6 +387,8 @@ extern uint8_t modbusExchangeBits(volatile uint8_t *ptrToInArray, uint16_t start
 */
 extern uint8_t modbusExchangeRegisters(volatile uint16_t *ptrToInArray, uint16_t startAddress, uint16_t size);
 
+uint8_t modbusExchangeString(volatile char* str, uint8_t size);
+
 /* @brief: returns 1 if data location adr is touched by current command
 *
 *         Arguments: - adr: address of the data object
@@ -398,4 +406,6 @@ extern uint8_t modbusIsRangeInRange(uint16_t startAdr, uint16_t lastAdr);
 
 extern volatile uint16_t modbusDataAmount;
 extern volatile uint16_t modbusDataLocation;
+
+void modbusHandleDeviceId();
 #endif