Varec 8300 series, Installation And Operation Manual, Page: 82 / 150

Tank Gate Interface
72 Installation and Operations Manual
5.9.2 Application
The MSCAN point provides status information for the communications with any Modbus devices
used with the 8303 TGI or the 8212 TRL/2. For the Model 8203, two MSCAN points are created
at initialization when the motherboard detects the Model 8203. The point number created for
each MSCAN point will correspond to the following table (the Module number is 1):
Note The 8212 TRL/2 only has ONE MSCAN. Chan 1 is MSCAN.01.
Use the Upload command from the Config Menu to retrieve the data from the MSCAN point or
any other points created automatically by the 8303 TGI.
The MSCAN point acts as a Modbus Master Protocol Handler (MSCAN) and works in conjunction
with MIREG, MFPREG, MG5000, and other Modbus slave points. The Modbus Master Protocol
Handler (MSCAN) sequentially processes these points, issuing data requests according to the ID,
Addr and Size parameters. The MSCAN point provides dynamic information regarding the
current request and total number of requests and errors.
The Chan parameters of the Modbus slave interface points must correspond with the Chan
parameters of the applicable MSCAN point. For example, assume that switch SW1 on the Model
8203 is set to address 1. If a MTS MTG gauge is physically connected to terminal connector J2
(COM Channel A) on the Model 8203, the MG5000 point for that gauge must be set to Chan 1.
The NumRequests parameter gives the total number of requests attempted, while the NumTrans
gives the number of completed transactions. The ID represent the current device address being
scanned. The Pnt parameter is the Tag of the point being scanned.
Cmd Current command. Values include:
1 - Read Output Status
2 - Read Input Status
3 - Read Output Registers
4 - Read Input Registers
5 - Force Single Coil
6 - Preset Single Register
15 - Force Multiple Coils
16 - Preset Multiple Registers
Pnt Point currently being scanned. Examples include the MG5000, MIREG or
MFPREG points.
NumRequests Number of scan requests since the last reset
NumTrans Number of completed transactions
NumComErrors Number of requests with communications or context errors.
NumTimeouts Number of requests that did not receive a response.
NumScanList Number of devices in the Scan List
PntCheckSum CRC-16 Checksum of point's static Configuration Parameters
Dynamic Parameters Function
Channel Point Number
Chan 1
Chan 2 MSCAN.01
MSCAN.02