GE P485 - Manual (Page 53)

ADVANCED FUNCTIONS
P485 MODBUS TO PROFIBUS CONVERTER – USER GUIDE 8–3
STATUS CODES The status codes are described in the following table.
HANDSHAKING
PROCEDURE
The handshake bits are used to indicate any changes in the status and control registers.
The procedure below must be followed for all changes to these registers with the exception
of the handshake bits themselves (bits 14 and 15).
Figure 8-1: Handshaking flowchart
Code Error Description
0x00 Re-transmission Number of re-transmissions. Reports the total number of
re-transmissions on the subnetwork
0x01 Single node missing Slave address of the missing node. Reports if a node is
missing
0x02 Multiple nodes
missing Number of missing nodes. Reports if multiple nodes are
missing
0x03 Overrun Slave address of the node that sent too much data.
Reports if more data than expected was received from a
node
0x04 Other error Slave address. Reports unidentified node
0x1F No error Normal Condition
Start
Equal?
Write to Control Register
Compare SR_HS_CONFIRM with
CR_HS_SEND
Toggle CR_HS_SEND
End
Set CR_HS_CONFIRM to
SR_HS_SEND
End
Yes
No
Start
Equal?
Read Status Register
Compare CR_HS_CONFIRM with
SR_HS_SEND
No
Yes
Status Register Reads Control Register Writes